Ciaphas Cain/WMG

Ciaphas Cain is the 40th millennium reincarnation of Edmund Blackadder.
Cain is Blackadder and Jurgen is Baldrick. It makes a ridiculous amount of sense if you think about it. This also means that Black Adder itself is set in the past of the 40k universe...which is probably a poison oak epileptic tree if you think about it.
 * Like everything else in the galaxy, Baldrick has clear taken several levels in badass. Also Blackadder respects him an whole lot more now.

Ciaphas Cain knows exactly what he's doing; he really is Just That Good.
What, you think he's a reliable narrator? He is very aware that he lives in a Crapsack World, so if he were to acknowledge heroics, especially to the Inquisition, he'd die very, very quickly. Or worse. He's also aware the only way to counter GRIMDARK is the Rule of Funny. No, no. Anything that he does that is heroic is actually self-serving cowardice and/or sneakiness. Really! So he fills his "true" biography that he knows will fall into the hands of the Inquisition with lies that don't matter; and his lover, Inquisitor Vail, debunks said non-politically dangerous lies. All the while hiding in plain view the fact that everything he does is Just As Planned.
 * He really is the Divine Will of the Emperor, by the way, but he tries not to think about that.
 * He isn't, but he convinced the universe he is. His faked death was part of a Xanatos Gambit to defeat Tzeentch.
 * Did you really think that he's listed on active duty despite his own funeral for reasons of paperwork? No, this is a sign to the faithful to have hope.
 * I think he downplays his heroics not because he's modest (or just modest), but because he's desperately trying (and failing) to downplay his abilities so that he doesn't get sent to the front lines of the crapsackiest of Crapsack Worlds all the time.
 * Possibly he is himself convinced that courage means total foolhardiness, and that his evident prudence is not a virtue but actually cowardice.
 * This is hardly inconsistent with the prevailing culture of the Imperium. The Guard encourages its troops to view themselves as expendable because they plan to expend them in human wave attacks; the Inquisition places practically no value on human life and the official line of propaganda is that any amount of death is worth it if the mission is accomplished. The church goes on and on about death in the service of the Emperor. Most of the major institutions of the Imperium do tell the average Imperial citizen to take loyalty to the Emperor to the point of near-suicidal foolhardiness; why should Cain be any different?
 * I find that Cain's narratives are often filled with examples of 'he doth protest too much.' Think about it, every time Cain takes actions that are pretty obviously going to put him at risk or are genuinely heroic, he goes out of his way to justify it with some way overly elaborate excuse as to why it was a good decision from the coward's point of view Every. Single. Time. As someone else previously noted, Cain just has a strong sense of self-preservation, for both him and the people he's leading, which leads to some serious Values Dissonance in the WH40K universe. The only other explanations are that Cain's judgment as far as keeping himself from danger is ridiculously poor, or that he's trying so hard to avoid danger that his efforts actually end up as counterproductive, putting him in more danger than he would be in otherwise, neither of which seem to jive with just how competent Cain is when the chips are down. Adding to this is the fact that in spite of how he describes his actions in his character defining monologue (enshrined on the Fake Ultimate Hero page), when we get direct descriptions of Cain in action, he always seems to be in the thick of it, going toe to toe with the enemies of the Emperor, occasionally in close combat, and is rarely ever found hiding behind cover, just waiting for the shooting to stop, although he always seems to go out of his way to find or invent extenuating circumstances that justify why he wasn't engaging in his "favorite tactic."
 * Whatever goes on in his head Cain's reflexes are heroic. When the ice gives way under Penlan he grips her wrist more tightly and ends up getting pulled down with her. When a cave-in seals him off from his Guards he tries to dig through the rubble to them. His unthinking reactions are as selfless as his reputation.

The techpriest Logash hasn't seen the last of the Necrons.

 * Consider: Logash goes insane upon seeing the Necrons. At first he's giddy, viewing them as religious guardians of sacred mysteries, but his tune changes once they slaughter the rest of his cogboy companions. So far, so good. After the trauma, he leaves the ice planet and quietly rises a bit in the ranks. He eventually ends up on serving on Mars. But not just anywhere. Oh no, his last known assignment is in the Noctis Labyrinthus. For those who know Warhammer 40k lore, it's a bit obvious where it goes from there, but I'll spell it out. The techpriests worship the Omnissiah, a machine god who they claim is an aspect of the Emperor. However, there is evidence that the Omnissiah is in fact one of the C'Tan called the Void Dragon. The C'Tan are the masters and creators of the Necrons. Even better, the Void Dragon is said to rest - where else - on Mars in the Noctis Labyrinthus. In other words, Logash ends up in the best place in the universe to get more acquainted with the Necrons and get more intimate with the man downstairs.
 * Further guess: this is exactly what the author wanted us to deduce from that footnote... Heck, it's practically canon.

Perlia is a dumping ground for former members of Inquisitorial retinues.
Or at least it is by the time of Cain's Last Stand. Amongst the people we see working at the Schola progentium are a pragmatic former Celestian, a possible former Inquisitorial Storm Trooper, a former Naval Admiral and a bonafide HERO OF THE IMPERIUM! whom we know served the Ordo Xenos on occasion. Even outside the Schola, we have an elderly Imperial Guard veteran who claims to be from Cadia. Who lets loose the battlecry of the Tanith First and Only. Gaunts Ghosts is set more than two hundred years prior to the novel in question, and Cain references receiving treatments from the Inquisition to keep him at his physical prime despite pushing somewhere in the range of a hundred. Bit too much for coincidence, no?
 * It fits within Inquisitorial reasoning, too. Not only do their prized veterans get a comfortable retirement, but their presence adds additional security if the Shadowlight is threatened.

Gunner Jurgen's status as a blank is directly or at least partly responsible for his apparent ugliness and lack of hygiene.
Canonically, most humans are at least mildly warp-sensitive; this is why Pariahs cause such mind-numbing terror and loathing in anyone they meet. Intuitive traits such as being a good "judge of character" are often ascribed to this warp-sense. Even blanks are often described as being naturally disliked by others - probably because the psychic-sense that humans normally use to form intuitive judgments about others don't work as well, so the blank always feels off to humans. On one occasion in Death Or Glory Jurgen is described as already looking as dirty as he ever does, almost immediately after bathing. It's possible that the reason others perceive him as dirtier than them (in a desert, immediately after bathing) is because he is a Blank and thus lacks the normal filters on how people perceive each other. For that matter, his lack of apparent education and his seeming disregard for hygeine are probably related as well; Jurgen presumably realized at an early age that people would never care for him, and simply decided to neglect normal courtesies as worthless in his case. Also, he pretty much destroys anything.
 * I've always assumed that to be the source of some of his issues, mostly the smell. There is also the fact that Jurgen's effect only works on Cain when he can smell him.
 * This theory seems quite possible. Similarily, in the Ravenor series, Wystan Frauka is a deeply unpleasant (not evil, just rude, boorish, and arrogant) person. But he has his blank limiter, so that may well shoot this one.
 * Alizabeth Bequin, despite being a very attractive woman, has similar (but somewhat more mild) problems to Jurgen in the Eisenhorn trilogy. So yes, I think the blank status has something to do with it.
 * This is confirmed by the rules for the blank character trait in the 40K tabletop RPG Dark Heresy. Characters with this trait, along with their blank aspects, receive a penalty to their Fellowship characteristic. This is similar to the Charisma stat from Dungeons and Dragons, as it affects social skills. Hence why Jurgan is the way he is.

Jurgen is actually the Chaos God Nurgle in disguise.
His odor, multiple skin diseases, and lack of personal hygiene are trademark Nurgle signs. Furthermore, his being a blank is actually just his psychic powers nullifying other psykers. He travels around with Cain to battle his enemies. The times they do fight against Chaos, its either Slaanesh or Khorne, and one time they actually encounter Nurgle troops, they end up killing their Slaanesh enemies.

Ciaphas Cain and Jurgen are the Chosen Ones. . . of the C'Tan Deceiver.
The very existence of Jurgen's blank status is a result of things going Exactly as Planned by the Deceiver. Two of Cain's three encounters with the Necrons involved them opening up second fronts on an enemy that was otherwise seconds away from punching his ticket. In retrospect, the Deceiver's strategy would seem obvious: pump up an intelligent coward as a hero, then attach one of the fruits of his eons-long master plan for fighting Chaos to him. Cain will have to act to defend the reputation that the Deceiver built for him, dragging Jurgen with him because he knows a blank provides his single best chance for survival. As a result, Jurgen is turned into a perpetual Spanner in The Works, constantly being thrust into situations where he'll do maximum damage to whatever master plan Chaos has come up with this week.

The loss of Simia Orchalchae was considered acceptable by the Deceiver. He had all the pieces in place, and was willing to bank on the future potential of his strategic pawns. Moreover, giving Cain the win there would cement the legend that was being created around him. The defenses of Adumbria and of the Shadowlight bear out this assessment. At this point, the cycle has become self-sustaining and requires only minimal upkeep from the Deceiver himself. Cain will defend his reputation and drag Jurgen along to defend his life simply out of habit. There was only one crucial situation, in Cain's Last Stand, where the situation was too urgent for subtlety and the Deceiver tipped his hand with the too-timely Necron counteroffensive. It's part of the Deceiver's plan to keep Cain and Jurgen alive as long as reasonably possible. As long as they exist, they'll keep getting thrown into situations where they can royally gum up the works for Chaos.

Basically, Cain is an Unwitting Pawn in the best way. It's the point of the exercise for him to be the primary beneficiary of this grand scheme, despite the fact that Jurgen is it's primary enabler. By building up the figure of the dashing, heroic Commissar Cain, Deceiver uses him as a smoke screen to draw attention away from Jurgen.

Ciaphas Cain and Co are from the less GRIMDARK part of the Galaxy.
It's a galaxy; bloody immense place. Ciaphas Cain is from the normal part, and they think the guys from the GRIMDARK part are crazy.
 * Actually, not terribly unlikely. Cain encounters some (stereotypical) Sisters of Battle during Duty Calls and he is clearly not particularly impressed. Nor is Amberley Vail, who frequently makes snarky digs at the expense of excessive and blundering, kill-em-all-and-let-the-Emperor-sort-'em-out style Inquisitors.
 * Objectively, the depiction of the setting is just as GRIMDARK as any other. Servitors are mentioned causally, war, destruction and death are constants, there is always a new enemy lurking around the corner and almost always a second one just behind them, fanaticism and relentless propaganda are the norm (Vail casually comments once about a children's book she read that depicts heretics being immolated with flamethrowers) and entire planets are regularly on the brink of destruction. Basically the only thing that is different is Cain himself, both his humourous narrative and preternatural skill and competence, both preventing the more devastating aspects common to the setting from occuring and shielding the reader from the ones that do. In effect, Cain creates his own bubble that temporarily nullifies the GRIMDARK (as if we needed more evidence that he truly is the Hero of the Imperium).
 * Really, the comments here are both true. It's definitely a Crapsack World matching that of a lot of other novels, but unlike some of the more overheated descriptions in game materials, the Guard units and planets Cain deals with are neither mismanaged into the ground nor exploited to the point that Chaos starts looking preferable.

Ciaphas Cain is the embodiment of the Emperor's will.
Praise be to our most beneficent God-Emperor, who has sent his prophet, Ciaphas Cain, to be a leader of heroes against the most evil of the ruinous powers. It would be a great theological boon if we were able to study his writings in detail.
 * Speaking as an out-of-universe observer who has read his writings...That's not that much of an impossibility.
 * He's certainly got a behavioral resemblance to Gideon.

Ferik Jurgen is the Anti-Haruhi.
Consider: Suzumiya Haruhi is arrogant, short-tempered, very controlling, and capable of altering reality to suit her will. Gunner Jurgen is selfless, laid-back, willing to take orders without question, and capable of nullifying Warp powers (i.e. those that would allow one to alter reality).
 * Alternately, Jurgen is not only the Anti-Haruhi, but Kyon as well. Both are laid back, natural followers, similarly bland features, and share the astonishing ability to secure something that at least resembles normality despite the chaotic worlds they live in. And you can just go wild from there...

Jurgen is the Emperor.
The Throne doesn't work so well as the priests think, it merely slowed his reincarnation. His surface traits are merely a disguise, and his Blank status is merely a cover for the use of much more powerful but subtle Psyker abilities. Being Cain's right-hand man is merely a convenient way to get around and de-emphasize his own actions-- all the focus is on the HERO OF THE IMPERIUM, who notices his slovenly dogsbody? Jurgen secretly protects and guides Cain, accounting for Cain's extremes of good and bad luck; he gets Cain (and thus himself) to wherever the greatest threat to Humanity is, and helps him overcome it (or overcomes the real threat behind the scenes while Cain deals with the more obvious physical danger). Ciaphas Cain (to Jurgen): "I doubt the Emperor Himself could have slowed that one down." Jurgen: "Probably not, sir, ..." A bit of dry humor there from the Emperor Himself?
 * From The Last Ditch.


 * Alternatively, Jurgen is one of the Missing Primarchs; his jaunt through the Warp not only resulted in him becoming a Blank but shrunk him considerably, though keeping his skill and resilience intact. Being a Blank, not even the Emperor could detect him and he remained undiscovered, the Legion derived from him collapsing due to lack of geneseed and he only learns about the Imperium and the Emperor long after the Horus Heresy. He thus decides to join the Imperial Guard and fight against the enemies of humanity in the Emperor's name, devoted totally to Him and His doctrine (not knowing that Imperial Doctrine and the Emperor's Doctrine are not quite the same thing). Eventually he endeavours to locate promising individuals and assist them in any way he can, protecting them and bolstering their reputation to ensure that they can fight and lead unhindered, from Thor to Macharius to maybe even Creed, Cain one of a long line of Heroes of the Imperium he has served without notice.

Ciaphas Cain is the reincarnation of Big Boss.
Cain is considered the greatest soldier of his time, so was Big Boss. Both were considered awesome leaders who fought side by side and often ahead of their soldiers. Both look and fight like far younger men. Should I go on? Apparently, Big Boss was so awesome, he was reincarnated as the HERO OF THE IMPERIUM, to fight in the toughest battles of the universe. The God Emperor only wishes Cain was the embodiment of his will.
 * Presumably the experiences of Big Boss's other incarnations in the intervening centuries enabled him to work the Blood Knight out of his system.
 * It's presumable that this is also shaped by their different experiences within the military. Boss was betrayed by his government, and grew kinda bitter. Ciaphas was treated with (tanna) tea, dumplings, and insane battlefields. But they definately have the same fighting spirit, and fairly similar tactics (Boss's M1911A1 and CQC knife is comparable to Cain's Laspistol and Chainsword combination, both tend to try to be sneaky before starting to blow stuff up.

The God Emperor is the reincarnation of Ciaphas Cain.
Following Cain's death, he outruns the Warp demons sent to claim his soul. Then, without any physical body to slow him down, he keeps running, eventually escaping from the Warp and passing into a welcoming-and strongly psychic human mind on earth almost 50000 years beforehis death. He waits out the centuries, waiting for the Imperium to emerge at the end of the Age of Strife. But, when the Age shows no signs of ending, he creates it himself out of a desire to survive. Remembering the many soldiers who died valiantly, but uselessly, in his campaigns, he seeks to create soldiers who are virtually immortal-the Space Marines. However, because he also knows how this all turns out, he provides himself with a few reinforcements for when things get really bad: the two missing Space Marine legions, hidden only Cain-knows-where. In fact, the only thing he didn't plan for was the psychic dissonance caused by his souls occupying two places at the same time. But there will come a day, following Cain's first "death", when the Golden Throne fails, and, with his spirit free once more, Ciaphas Cain, IMMORTAL GOD-EMPEROR OF MANKIND, will return to the mortal realm, call upon the missing legions. Then, he will stand against the forces that seek to tear the Imperium apart on every side, and do the only thing he knows how to do: he'll win.

Cain isn't dead.
He's in a secret location under Amberley's supervision.
 * More probably, he's just finally got his long overdue promotion, and doesn't have to hide the rosette anymore. ;) His "death" was just a cover that allowed the newly baked member of His Divine Majesty's Most Holy Ordo Xenos to continue his service to his Eternal Lord.
 * Inquisitor Ciaphas Cain... Emperor help us. Emperor help us all.
 * This makes a suspiciously large amount of sense. To take it further, firstly it means they've got an inquisitor who has his head screwed on for a change and wants a more peaceful, safer empire (for himself at least). Add in that Amberley laments in the footnotes of Caves of Ice that the Adeptus Mechanicus is up to something on Mars and wants to know why someone isn't asking the pointed questions; well who do we know that has long and terrifying history of surviving Necrons and mechanical menaces, that isn't intimidated by the mecha-loonies, who can never resist poking his nose in even when he knows he shouldn't, and is bloody cheeky to boot?
 * Well, nobody. Cain is intimidated, and his problem isn't "inability to resist poking his nose in," it's "inability to avoid getting his nose poked in." Still, that's quibbling...

Sulla has a distinct crush on Cain.
Not much of a guess, I know, but look at the evidence. The main page notes she goes from appearing to hate his guts to determined to prove herself to him. It looks to me, from the evidence, as a mix of a crush and hero worship.
 * Hero worship, yes, but there's no evidence of a crush-- more like she sees him as a father figure.
 * Subtle indication that she is- think of any female character who is interested in Ciaphas Cain and vice versa who is not Amberley Vail. They are all negatively portrayed (Ms Tayber is a Genki Girl Geek, etc.) Who's editing the papers with the power of changing the characterization of certain characters? And is also a little jealous?
 * A better point on the theory that Amberley is editing the details of Cain's love life in his memoirs is the fact that every single story in which Cain has a lover who is not Amberley takes place before they meet. Then the question is whether this is because Cain became monogamous after meeting Amberley, whether Amberley has edited out all scenes where he sleeps with other women after their meeting, or whether she just refuses to publish the stories in which he arguably cheats on her.
 * Wait, a genki girl geek is a negative portrayal?

The whole series is a Self-Insert Fic by Amberley Vail.
I can't be the first to think of this, can I?
 * This would be horrible.
 * But hilariously in tune with the grimdark universe.
 * Hahaha, yes, this is the best theory. Next time I read the novels I'll see how it works with that reading/textual backing.
 * And their first meeting now resembles how a fangirl would write her favorite character's reaction to her Mary Sue self-insert. Goddammit, you ruined for me!
 * Proven wrong because the sexual relationship is implied and its obvious where confirmations were cut out but any self insert fic would imply it would outwright state the events.
 * Not conclusive disproof; she could just be an exceptionally subtle and self-restrained Self-Insert Fic author. Note that, although the sexual part of the relationship between her and Cain is never made explicit, the cut outs are timed in such a way that the existence of their sexual relationship is quite unambiguous. In other words, she's doing the literary equivalent of the Sexy Discretion Shot version of Fade to Black.
 * Perhaps something like this?
 * See, as the original creator of this theory (and a little cheerfully baffled by its apparent popularity), I think it's actually a lot funnier if Amberley is an Inquisitor, not a teenager. Come on, you can't tell me that the idea of an Inquisitor writing self-insert fanfic with her favorite hero isn't absolutely hilarious.
 * Also, her character is what you'd expect from that: beautiful, completely badass, wears a suit of golden power armour, has the authority to do pretty what she likes and even has her own starship. Plus, the canon protagonist is love with her and she saves his life a few times. Total Mary Sue self-insert, right?
 * Needs a talking animal though.

Ciaphas Cain is actually Rincewind
Seriously, with as long as Rincewind has lived, and the fact that he's been shunted into various dimensions, including ours... the cunning, and the cowardlines, and the heroism, that can't be a coincidence.
 * You could build this out to Discworld actually being in the 40k universe. Dangerous Wizards feared and untrusted by all -> Psykers, Dungeon Dimensions inhabited by indescribably unpleasant chittering things -> The Warp with its assorted daemons.
 * must be extremely busy, then.

Cain's original memoirs included intimate details of his relationship with Amberley Vail.
These have been edited out by Amberley. Not that she's too concerned about concealing their relationship from the Inquisition (any Inquisitor who can't figure it out from what's in there should be fired), but she doesn't feel comfortable with anyone else reading the details of exactly how good Cain's first night with her was. Her personal copy contains these details, and she peruses them from time to time, especially if she hasn't seen Ciaphas in a while.
 * Likely points for editing include the ends of For The Emperor and Caves Of Ice, and the midpoint of Duty Calls (page 174 in the paperback).

Cain, not Abaddon, is the true Champion of Chaos Undivided.
How does this work? Simple. Look at Cain - honor, martial strength, obscene kill count, best chainsword user in the entire Imperial Guard... Looks like the work of Khorne. Ability to appear in precise to spot to ruin almost any plot of the enemy, no matter how convoluted it is? That, and his huge (for a Commissar, that is) knowledge about Chaos and his apparent invulnerability? Tzeentch. Now, for Jurgen - he shows markings of being chosen both by Nurgle (really, it's Jurgen) and Slaanesh (his holo-picts with you-know-what, plus suggestions of what he does with them). Together, they battle the enemies of the Imperium - but only to stave off suspicions. After all, who will suspect heroic Commissar? But look at what Cain actually does - every place he walks through ends up wrecked. He kills Orks/Necrons/Tyrannids that are threat to Chaos, too. On the rare occasions he ends up battling Chaos, Imperium wins... by killing off a few useless pawns. Really, every victory Cain makes saps Imperium's strength bit by bit, both by losses it incurred, and by overstretch, as it still has to guard/reinforce all places Cain had "saved". Thus, in a thousand years, when God Emperor will finally awake... he will lose, as all tiny dents made by Cain will undermine Imperium's strength in critical moment. Just as planned. Thus, Abaddon is just a loser making loud Black Crusades that are designed (from the start) to accomplish nothing but divert Imperium's eyes. Now, if only Amberley was from Malleus, not Xenos, the Imperium might have spotted that treachery...
 * By this standard, anyone could be a champion of Chaos Undivided... I mean come on, "owns a porn collection" is a mark of being chosen by Slaanesh?
 * I would say more his ability to seduce any woman he sees.
 * Explain "The Last Stand"...
 * If you were the true champion of Chaos, would you want some pathetic little Hitler Expy to steal your thunder and muck up your plans?

Cain, Jurgen, and possibly Amberly, are spiral beings.

 * In a universe where nearly everyone is tainted by one force or another, these three have managed to remain hopeful, brave, loyal, and basically the nicest people in the Imperium. Cain was even able to resist a Chaos temptation WITHOUT Jurgen's help on a couple of occasions. Amberly attracts and takes in a ragtag group of misfits and actually values them. There is no Warp, WAAGH, or Emperor's Will within those three, but Spiral energy and that's what has saved them all this time.
 * Don't believe in Cain! Believe in Jurgen who believes in Cain!
 * The weird part is where you decide to apply the parallels:
 * Ciaphas is Kamina. Natural talent and an inspiring badass public persona to conceal the fact that he's essentially terrified all the time, ultimately Becoming the Mask.
 * Shimon is split between two characters.
 * Jurgen is essentially a Shimon who never grew into his own niche. Extraordinary supernatural talent, intense loyalty to his friend, and surprising combat effectiveness mingled with poor social skills and little intellectual cultivation.
 * The other half of Shimon, post-timeskip Shimon specifically, goes to Jenit Sulla. Inspiring, capable leader with a penchant for aggressive, damn-the-risk tactics that nonetheless tend to work out anyways.
 * Amberley is harder to assign a parallel to.

Commissar Ciaphas Cain is a missing Primarch.
No one knows where he is from, who his parents are and how the hell he got into the Scholarium to become a Commissar in the first place. He is probably from a Hive World, but no one knows which one. He has an excellent grasp of tactics (think of all those subtle ways he shields himself with troopers!). He is one of the best swordsmen in the Guard, if not the very best. He always, always knows when a bad situations is about to occur. He has an instinctive caring for his subordinates, even though he pretends he doesn't. He's saved worlds from Orks, from Tyranids, often single-handedly. And he has never lost to anyone he had the slimmest chance to win of.
 * As much as that idea is terribly appealing, he developed too slowly for that to work. The Primarchs had a freakishly quick progression to physical maturity, where as Cain seems to have grown at a normal rate. Unless his Warp mutation was comparatively delayed growth the connections aren't strong enough. It would be wonderful to have such a gleefully amoral Primarch however.
 * How do we know he didn't grow up freakishly fast? Amberly notes frequently how extremely little is known about his childhood before his commissarial training, and even that isn't commented on much; all we know is that in all probability he was raised on a hive world. Plus, he's about as far from amoral as you can get, he just has self-doubts that have convinced him otherwise. Read what he says he does in his journals, not what he says he is in his journal, since he's such an Unreliable Narrator- he's one of the most moral people in the Imperium, based on those actions. As Amberly notes, it never even occurs to him to shoot through his subordinates, for example.

Jurgen and Corporal Nobbs are somehow related
If only because their levels of grungy-ness are too astronomical for them not to be connected.
 * It follows, given that the sense of grungyness is magnified by Jurgen's nature as a Blank, that Corporal Nobbs is also a Blank. Thank goodness none of the Wizards at Unseen University have ever tried casting a spell on him.
 * But their magic isn't Warp-based. However, with Orks running around these days, it's plausible.

Cain will become a Warp Entity after his death
Think about it, belief has a strong influence in the 40kverse. Not only is he a HERO OF THE IMPERIUM, but he has his own cult among the Tallarns. Once he passes on all that Belief will coalasce, and instead of joining the Emperor Cain will find himself as a warp entity/angel in the Immaterium. (and probably highly annoyed to as he'd likely be summoned to aid Imperial forces in even MORE perilous situations...)
 * And he will actually be quite terrifying, because 1.) Jurgen WILL eventually follow him, somehow, and make him proof against other Warp Entities & 2.) because he has spent so much time with Jurgen he will have built up an immunity to regular Blanks rendering them useless to use against him.

Jenit Sulla is Cain's younger sister.
Or possibly daughter. Either way, she's basically his Distaff Counterpart and secret blood relation.

Fact: we don't know anything about Cain's parents. The part about being orphaned is true, as is the part about growing up on a hive world. So is the part about his parents being Guardsmen. However, he didn't grow up with them. They served in a mixed unit -- much like the 597th -- and Cain was a mistake that they covered up by abandoning him to the underhive. Eventually, they retired and settled down on Valhalla, at last having a child that they kept. A daughter they named "Jenit".

Flash forward centuries later. Both Cain and Sulla have wildly improbable careers, accompanied by poorly-written but wildly popular public memoirs... that completely cover up the real truth that both of them spent all their years of service scared witless and desperately trying to avoid danger, building up Big Damn Hero personae both to cover up the truth and as a means of ensuring a constant supply of cannon fodder willing to leap to their defense.

Somewhere out there is another Inquisitor who carried on a decades-long romance with Sulla, uncovering her secret memoirs and editing them for circulation among his Inquisitorial comrades after his death.
 * Given that Cain apparently went through quite a few mistresses in his early years as a Commissar (This appears to have tapered off in the years after he met Amberley, unless she has deliberately chosen to not publish the stories where he sleeps with other women after their first meeting), leaving them behind as his deployments took him away from whatever planet or ship the women in question lived on, it's entirely possible that he had children that he never knowingly met. Sulla couldn't be one of those, however: Even if Cain had fathered her shortly after becoming a Commissar, she would have been ten or eleven when he was assigned to the 296th/301st.
 * Well it's acknowledged in series that all the time Cain's spend travelling in the warp's made his age rather ambiguous, and given he has no known home (until he settled on Perlia anyway) he hasn't any real reference point. It's entirely possible he fathered a child and spent a large chunk of his or her lifetime in the warp, or said child travelled through the warp and aged differently herself (if we assume it was one of his younger, more risky liasons with other military figures it's possible young Sulla could have spent time travelling through the warp with her mother and ended up a few years older). Hell, for all we know he's the Lord General's dad.
 * If anyone knows a way to contact Sandy Mitchel, send him this WMG. I am pretty sure this would make his day!
 * Point in favour of the Cain's sister theory. In Caves Of Ice, notorious Blood Knight bordering on Leeroy Jenkins Sulla had her squad evacuated on the first shuttle out of there in the face of advancing orks and necrons. Something Cain himself was planning on doing if he hadn't felt the need to shore up his reputation. Sulla probably spent the rest of the journey home very loudly and publicly lamenting being safely evacuated, thus convincing Cain of her own bloodthirsty rep so he didn't notice she'd outdone him in the run-like-hell stakes.

Following on from the previous WMG; Commissar Donnal was Cain's son
Mainly the same reasoning; Cain Really Gets Around and he's pretty similar.

The Kryptmann Gambit is going to end badly
The Kryptmann Gambit was a scheme to weaken the latest Tyranid Hive Fleet by luring it into Ork-held territory, and hopefully getting the Orks to thin out the Tyranid ranks a little without any damage being done to Imperium worlds. It seems a sensible idea, so long as the Tyranids don't manage to take and consume the Ork planets.

But there's a problem with this scheme. In The Emperor's Finest, Cain encountered a brood of Genestealers on the Spawn of Damnation that were implanting the Ork raiding party living on the same hulk with Genestealer implants, with the intent that the Orks would turn some of the people they end up fighting on the next planet they raid into Genestealers, with the defenders being unaware that their attackers weren't ordinary Orks. Sending a Hive Fleet through Ork territory creates the very real possibility that this will happen with any planet the Tyranids don't manage to consume outright. This will cause a lot of problems for the Imperium worlds bordering the Ork-held territories in the generations to come.
 * I thought that was canon in the larger 40K materials anyway?
 * This is actually addressed in The Last Ditch. Vail comments that

Jurgen's blank aura makes those in his vicinity knurd.
Discworld establishes the idea that relatively few people truly see the world as it actually is. In Warhammer 40000, things like a good sense of intution or being a good judge of character are actually manifestations of humans' natural psychic potential, explaining why blanks are inherently unlikable on first impression- humans see them as they truly are from an abstract perspective, without the sense of kinship and common humanity.

The shadowlight can turn psykers off as well as on.
That's why the necrons want it so much. Indeed, the reason why there are psykers in the future but not now is that something happened to the shadowlight -- it's the source of all psykers in the galaxy.

Jurgon is a Ratling/Ogryn hybrid.
Smelly, blindly loyal, focused and blunt to the point of near stupidity, good at combat with big weapons. Check. Excellent scavenger, sneaky when he has to be, obsession with porn slates, good marksman, good cook. Check. Just tell me a meltagun isn't the kind of thing you'd expect an Ogryn "sniper" or a Ratling demolitions expert to use.

Try not to think about the implications surrounding his conception.


 * He did get hit on by an Ogryn once...

"Jinxie" is decended from an Afriel Strain guardsman
Apart from the obvious supernatural bad luck, the Afriel Strain's main feature is albinism; something that wouldn't be as visible among the pale, blonde Valhalyns. Maybe one of them settled down and managed to have a family on a planet where they could hide their origins with nothing but a pair of coloured contacts...

Amberley is editing Cain's memoirs more than she lets on
Particularly about the parts concerning Cain's love life. Every non-Amberley love interest that actually contributes to the plot of a novel tends to have a pronounced character flaw, and there is absolutely no mention of Cain having any lovers other than Amberley in the years after they first meet.

Cain, and not Amberley, is self-editing Cain's memoirs
Come'on, he has an Inquisitor as a girlfriend. A person who's very job description is to sniff out secrets. The warp hath no fury than an Inquisitor scorned, after all.

Amberley is more hung up on Cain's death than she lets on
The Cain Archives, as Amberley puts it, is a mess. It is in no chronological order, and there are no chapters or indicators of any kind. Deciphering that work is probably a massive undertaking... but the Imperium is full of people well suited to the task (Amberley even drags around a scribe who could have easily done the deed). Why then does a Inquisitor, a rare resource better suited to sniff out heretics and enemies of the Imperium, be stuck editing some dead guy's words? Unless...
 * I always figured she did it in her spare time between cases. In particular Warp Travel between planets can take quite a long time and there isn't a whole lot she could be doing during that time anyway.

Cain is being used in a minor embezzlement scheme
Due to the numerous times that Cain was erroneously declared KIA only to turn up alive later, the military decided to keep him listed as alive and on active duty at all times. This has continued past his confirmed death and burial with full military honors. Because of this, that means he is still on the payroll even though he is no longer able to collect his pension. Somewhere in the system, some accountant has realized that there's a highly decorated Commissar with over a century's seniority who stopped claiming his pay, and then decided that since Cain doesn't appear to want it anymore, he might as well take it for himself.
 * Alternatively, Amberley is claiming Cain's pay for herself -- for the betterment of the Inquisition, of course...

Jurgen is much smarter and more important than even Cain realizes
He knows Cain better than almost anyone in the galaxy, possibly even better than Amberley. He's subtly manipulating Cain towards an unknown goal while appearing simple, helpful, unassuming, and incapable of anything other than literal interpretation of orders. He controls who gets to speak to or see Cain during regular business hours. He may even have realized his status as a blank years earlier and been using it to help Cain without the commissar ever realizing it.

Maybe the Tallarns have it wrong, and Jurgen is the true incarnation of the Emperor's will.

Because Cain is forever listed as Active Duty, Cain IS on Active Duty.
Even being dead is not a problem in a Universe where Faith can shape reality, Caipahs Cain, HERO OF THE IMPERIUM! will live on forever as a legendary figure whose fame and tales of ever more dangerous exploits guarantee that wherever the fighting is heaviest, whenever the dangers are most dire, whatever the threat to the Imperium itself! Ciaphas Cain! HERO OF THE IMPERIUM! will be there to turn the tide!


 * "I couldn't say no to an Inquisitor. Now I've got the fraking Emperor asking me to do stuff."

Ciaphas Cain is actually (unintentionally?) achieving (technically heretical) Sainthood status via his exploits right under the Inquisition's (this means YOU Amberly) nose!
Much like the pure zealous belief of the Sisters of Battle can summon Holy Living Saints of the Imperium to fight by their side, enough Guardsmen have heard of Cain and actually incorporate him in their traditions like Cain's Round, the Prophet Spoke: Frak This!, and more over time.

It will probably only be AFTER odd things start manifesting in battlefields across the Imperium that the Inquisition will take notice.

Fleeing troops chanting Cain's name will inexplicably find a tall man with a chainsword appear from no where to cover their retreat.

When leading a hopeless charge against a foul stronghold of heresy, screaming FRAK THIS! as a war cry can call forth a vision of the Prophet whose every las shot is the wrath of the Emperor against which no enemy can stand!

Even when deep in the heart of enemy territory, surrounded on all side, running out of everything., save one last cup of tea as an offering and know that you will find your way home.

And the reason why this happens to Cain and no other Hero of the Imperium?

Simple.

Cain actually CARES enough about survival (especially his own) and goes to great lengths to ensure that casualties are as few as possible, so not only does his fame spread as a Commissar who Cares, but he has sense enough to not lead his men into the meat grinder time and again, leading to him having more believers in the HERO of the IMPERIUM than there are Sisters of Battle.

Guardsmen may lack the pure zeal of a Sister of Battle, but as always, what they lack in quality, they make up for in quantity.

So a round of tea for Ciaphas Cain! HERO of the IMPERIUM!


 * Isn't the tradition of Cain's Round the belief that if you are diligent and train hard, Commissar Cain will see to it that you get extra beer? A more likely belief would be based on his comment on Perlia about the fact that the nearest mug of tanna was on the other side of an army of Orks and he was thirsty enough to go and get it - If some of your men are trapped behind enemy lines, prepare a mug of tea for the Commissar at your base. No matter how many kloms and how many enemies are between your trapped men and safety, Cain will see to it that they get home.
 * Alternatively, when a small group of guardsmen have been detached for a last ditch one-in-a-million chance sometimes they will be approached by a tall figure wearing the uniform of an Imperial Commissar who accompanies them to ensure that their mission is a success.

Cain's exploits are part of a plot by Tzeentch.
Because, come on, what isn't?

The ninth volume will concern the Tyrannic Wars
The second three books all concerned the Shadowlight to some extent. The seventh book concerned genestealers on a 5,000+ year old space hulk, while the eighth involved Tyrannids that had been dormant for at least 5,000 years (Well before the first confirmed sighting of a Tyranid). Since Cain mentioned being pulled from retirement to fight Tyranids in book six, given the Tyranid-centric nature of the last two books, this seems a logical theme for the next book.

In the ninth book, Mira will return.
She will also introduce her husband's heir (who's middle name will be Ciaphas, for the prestige mostly...or so she says). Said heir may or may not be rather tall and muscled, despite the governer and his mother's bulk, and pragmatigally cowardly.... The main reason for this WMG is that it follows the pattern of the last lot of books where a character/Love Interest appears again and introduces what is essentially younger version of Cain. Bonus points if Vail has a physical presence this time.
 * Since in the previous three book sets Amberley was a major character in one book, an extremely minor character in the second, and not present whatsoever in the third, and the current set has already had a book where she wasn't present and one where she was a minor character only appearing in person in the last chapter, she's due for a major role in the next book.

In any other universe Cain would be more of a traditional hero.
On this site we have collected more than enough evidence that Cain is a hero and will act heroically even when he has other options available to him. The reason he spends so much time denying his own heroism is because thanks to the 40K culture he believes that being afraid or having a sense self preservation makes you a coward. Because he has these things he believes that he is a coward therefore nothing he does is heroic. Most universes don't have this point of view, at least to this degree. If he was in another universe he would still act just as heroic, he just would not hate himself.

Cain is the reincarnation of Horatio Hornblower
Smart, talented, believes his reputation for heroism is undeserved despite the awesome things he does, encourages it anyway, has a habit of saying dramatic things for the sake of morale. The biggest differences are that Cain is a good deal more selfish and self-centered than Horatio, and he doesn't read briefings.
 * No, that would be Horatio Bugler, who has fought in some of the same campaigns as Cain, but has never actually met him.