Durarara!!/WMG

Aoba will become yandere for Mikado

 * Because Mikado already went yandere for Kida...

Mikado manages the online dating site that Tom Tanaka and Shizuo work for

 * It was mentioned that Mikado manages several online businesses for money

Certy is one of The Stig's cousins
...and it follows that The Stig is a Dullahan.

Izaya is an older alternate universe version of Araragi

 * Same voice, both don't get hurt easy (due to the after-effect vampirism), and both have a knack for understanding people. Additionally Izaya's casualness around Celty can be attributed to the fact that he has delt with the supernatural before. The divergence point from Bakemonogatari's timeline is his relationship with Senjougahara. Instead of following up with her after she admits to loving him, he passes up on her offer and later witnesses her in a relationship with Kanbaru, and feels a mix of envy and happiness. He realizes his love of human reaction and eventually develops an extended version of Oshino's attitude. He changes his name, fashion, hairstyle, and school. He manages to get his information network setup within a year, and meets Shizuo and Shinra at Raira. Like Araragi, Izaya has two sisters. Their name change can be attributed to the fact that they would want to help Araragi adjust to a new lifestyle.

Issac and Miria sold their life story to a Japanese studio.
It'd explain why there are ads for Baccano! throughout the show even though two of the main characters are around.
 * Feels more likely that somebody else from Baccano!'s immortal cast did that, considering that Isaac and Miria never quite figured out what was going on, and only realized they hadn't aged a day in 2001!
 * The light novels came out in 2003. Issac and Miria had a perfect amount of time to blabber about their story and have it turned into a show. Besides, who else would be stupid enough to do that?
 * Funny you should ask, because the answer to that would actually be Firo -- who's been shown telling the story to an unnamed Japanese tourist in 2002 in The Rolling Bootlegs. Hmmm...
 * So Miria, Isaac and Firo told their stories - which would make sense if you think about it: Our duo is not very bright, they can only tell their part of what happened (they did take the better part of a century to realize they are immortal, there's no way they knew the rest of the story). Firo does (at least the entire Immortal-part) and as for the rest (Jacuzzi, Chane and Vino), maybe the Daily Days did something to spread the rest of the story to Japanese anime producers...?

Mikado is a Vocaloid

 * ... Explain why, Troper?
 * Not the original troper, but it probably has to do with his surname, Ryuugamine. All Vocaloids with surnames have "ne" at the end of them. However, the "ne" in Mikado's case is part of the word 峰 "mine" and not 音　"ne"　like in 初音　Hatsune.
 * Counterexample: Neru Akita, Hiyama Kiyoteru, and Yuki Kaai. None of their names contain 'ne' for sound yet they're vocaloids.

Kasuka Heiwajima is directly descended from Huey Laforet.
Huey Laforet has a habit of fathering/grandfathering/great-grandfathering look-alikes, and damned if Kasuka doesn't have an eerie resemblance to him. It doesn't help that Huey has a great-grandson that looks and acts almost exactly like Kasuka.
 * So Shizuo's occasional moments of madness might be attributed to Claire.
 * Having Claire's genes would explain a lot about Shizuo in general. After all, in terms of superhuman abilities, throwing vending machines isn't that far removed from some of the stuff Claire does.
 * Maybe it's just me, but does anyone else see a resemblence between Luck Gandor and Seiji Yagiri?
 * Not to mention that Izaya could be either a Stanfield, Russo, or Spector; the guest extra who made the assault with the fireworks is Jacuzzi/Nice spawn (loves explosives but is too scared to use the big bombs), and  exhibits a fighting style similar to Chane.
 * In the ova, Kida looks a lot like Graham Specter

The characters are incarnations of the deities from Norse Mythology
Well, Celty might be a Valkyrie, and with his constant manipulation of others, Izaya seems an obvious fit for Loki, and maybe Shizuo is either Thor or Baldr- he hates Izaya on sight because of what Loki did to him. Anri is Freyja- one of her roles was leading the Valkeries, hence the sword she carries, and while Freya was a love goddess, since this is Japan, she was incarnated as a Moe schoolgirl. Kida also seems like a good Thor candidate, given his jovial manner and not being that bright. Finally, I could see Mikado as Odin- he pursues wisdom and is really good at getting people to follow him.
 * Following the theory, Shizuo would be more fit as Thor candidate. If I remember correctly, Thor is the kind of god who is not the brightest and Shizuo isn't the brightest character of the cast, either. Masaomi on the other hand just acts like an idiot - he is certainly not, there's more than meets the eye. And instead of Shizuo, Masaomi might have qualities to be Baldr/Baldur, since he is Izaya's so-called King Of Sacrifice. Baldr's death was what led to Ragnarok, too. It's debatable, though.
 * Alternatively, Anri is either a gender flipped version of Freyr or a combination of him and Freyja. After all, Freyr's sword was described as being "so good that it fights of itself"- reasonably close to Saika's abilities when one takes the control of its "children" into account.
 * Actually Shinra could be Odin. Friends with Loki (Izaya). Check. Some Trickster Archetype characteristic himself. Check. Close connection to the Valkyrie. Check.
 * Simon would fit Heimdall. Not only Heimdall was the guardian of the Bifrost, thus keeping Valhalla safe, but he was constantly Loki's rival in terms of his job and that he often was rarely fooled. He happens to be a key figure in keeping Ikkeburo in order when he appears and has gave Izaya several lectures. Fits him perfectly!
 * Wouldn't be the last time Heimdall was Black...

Izaya is Naoya
Naoya. Izaya looks JUST LIKE him. It also explains why Izaya
 * This troper is glad she's not the only one who saw this. They really do resemble each other, both appearance and personality wise, especially in the manga, where Izaya wears an out-of-place-looking coat/cloak thing all the time like Naoya does. They probably look similar mostly because Naoya and Izaya's character designs were done by the same guy...but still.
 * This troper thinks about the same thing, too, although she must disagrees with the whole Naoya's appearances being similar to Izaya's (Naoya was a basic White-Haired Pretty Boy while Izaya was more like Atsuro without a hat instead, but then again, ). Too bad that Izaya was not named as Kai or Kaien or something, though. Wait, so, does this make Mikado , then?

Izaya is an extremely out-of-his-mind Nozomu Itoshiki.
One too many cases of despair broke the teacher's mind and transformed him into a Magnificent Bastard with the desire to spread despair onto others.

Izaya is the physical manifestation of the dark side of a certain Timelord
After all, he does claim that he loves humans, and prefers observation to direct action in a chain of epic events. He only inteferes for his own amusement, contrary to the Doctor's usual practice of saving lives/civilizations/the universe. Also, he has an unusually eccentric charm to his personality, and people listen to him despite their own common sense.

Walker and Erika are Reality Warpers
Spoilers for Simon and Chief Chef's backstory: The reason? Because Walker and Erika didn't just guess their past, they willed it into existence. Kinda puts Walker and Erika's comments about "choosing" the bits reality they want to be real into a new light, huh?

As for why Shizuo/Izaya (or Kadota/Chikage) isn't canon if this is true, it's because they have to be in agreement for it to work.
 * So does that mean that when they were telling the story of the prince and the princess (which is Kida and Saki) does that mean that by telling the story, they made it reality?
 * Except that in the anime at least, they attempted to Retcon that part (you know, when they tell Kida ) but that doesn't seem to have worked. ... OH WAIT. Need to check that wording, but
 * Or it could be worded out as, since she was.

Shizuo and Kasuka have fae or otherwise supernatural ancestry
When Shinra is brought in to treat the quarter-Dullahan, he's amazed to find that the unusual properties her body has (Super Strength, an accelerated Healing Factor, and nigh-impenetrable muscle tissue) are almost identical to Shizuo's. The official explanations for Shizuo's Super Strength are a lack of mental blocks and plain old Charles Atlas Superpower, but what about his ability to bounce back from otherwise crippling injuries, or the fact that his body is tough enough to break steel scalpels? And his brother is hardly normal either, what with simultaneously being a hypercompetent Ace and an ice-cold, robotic Stoic.

The answer might be that the Heiwajimas aren't entirely human. Given that we know very little about their parents (other than that they're alive and they weren't abusive), and that human/nonhuman offspring have been proven to be possible via the aforementioned, it's entirely possible for both of them to have some inhuman blood themselves -- if not fae, then possibly Youkai or demonic (the Naritaverse is practically an Urban Fantasy Kitchen Sink, after all).
 * That makes a lot of sense. It might also explain why one is rage personified and the other totally unemotional since IIRC hybrids in folklore tended to be...odd.
 * This, of course, can also fit in with the above "Shizuo and Kasuka are Huey's descendants" theory. Huey's been shown to both use his own genetic material for some Homunculi (as demonstrated by Riza) and make some wacked-out hybrids (human/dolphin, anyone?). If he ever managed to get across some supernatural blood, there's no way in hell he'd resist the temptation. The result? One of Shizuo and Kasuka's parents.
 * Okay, due to the sheer amount of sense that this theory makes, with or without the Baccano connection, it is now this troper's head canon until the series proves otherwise. Also, if it does turn out to be true, then they kinda hope that the non-human contribution to the Heiwajima gene pool is some sort of fae, mainly because it'd probably be easier for Shizuo to deal with not being 100% human if the non-human part is something similar to his best friend.

Saika is possessed with the spirit of Graham Specter.
No seriously, listen to him talk and then listen to Saika talk about humanity. Considering Durarara and Baccano share the same universe, surely by the time of Durarara, Graham's been dead for a few years. Granted, I'm not sure why he'd be in a sword and not a wrench, but there you go.
 * Since Saika has been rumored to be around for a couple thousand years we can edit the theory alittle bit. Graham was one of the previous owners of Saika and his spirit became the predominant personality residing in it. Reinforcing the general theory is the fact that Graham idolized Ladd and is now looking for the closest thing. Angry, talkative, and strong? Sounds like Shizuo.

Izaya is actually Prussia from Axis Powers Hetalia.
I mean, he's not a country anymore, he's gotta have a lot of free time. He just got his hair dyed.
 * Assuming you're serious, this is highly unlikely in that Izaya not only has sisters, but also fears death. Prussia, who is also East Germany, cannot die. Even after North Italy/S.Italy united Feliciano and Romano both still exist, so... Jossed.
 * The above is a very valid point, but it being completly jossed is arguable. One thing to remeber about Hetalia is that very little of what people assume to be true is ever outright stated, and thus many things taken as Canon are just Fanon at the moment. It's never outright stated that Prussia is East Germany, or that nations are completely, entirely imortal. And if Prussia was East Germany, than he may have all the more reason to fear death as, unlike the Italy brothers, West Germany was pretty much taken as the Real Germany after the unification, adopting it's government, ect. So he could be holding on simply because of Ostalgie. But still as you said, Izaya does have sisters, and I personaly think the below Troper's idea has more merit.
 * This troper is inclined to suspect Izaya of being proof that at some point in the past Gilbert failed to keep it in his pants.

Izaya is Tite Kubo.
Because seriously, who else could match that level of stylishly evil Trolldom?
 * I SUPPORT THIS!!!
 * ME TOO!!

Yamaha will discover Psyche and Tsugaru, get Hiroshi Kamiya and Daisuke Ono, and turn them into Vocaloids.
There's gotta be a reason why they're drawn with nail polish so often.

Celty isn't actually a being from Celtic nor Norse mythology.
. This came to me suddenly when I watched Baccano! just now, the episode when. I mean, Celty's able to make fucking clothes with her smokin' power, Her memories as a Dullahan could be. Maybe it was some sort of. Maybe even those myths actually started.
 * With that train of thought, wouldn't that also make Saika like that as well? An alternate reading of this WMG would be that most supernatural beings in Narita-verse (Dullahanas, Demons, Saika,) are similar beings that simply just adapt to whatever culture they were in. For all we know The Vampires in Vamp! were granted their abilities the same way the Immortals in Baccano!.

Aoba snapped at Izumi because he was sexually abused.
His brother mentioned that he beat up Aoba often because of an inferiority complex. But then he mentioned that he went too far this one time and then Aoba got him back  Izumi then states that Aoba took all the physical abuse and never complained about it. When you put this info together, something that was out there like rape might have done it in. And since Izumi would, he might as do this.
 * Or perhaps he "kidnapped" and killed a beloved pet of Aoba's or something. That sounds a bit more in character and fare less Squick.
 * Why would Aoba have an animal? Aoba's backstory doesn't even mention that he had a pet at the time  Even if he did, I'm pretty sure pets aren't allowed in the area where he lived in. Plus, having a dog would be too OOC for Aoba.
 * Support. He was also going to  in front of a bunch of people. When Mikage stopped him, he said "Since you owe me one you are going to play with me, right?". He's obviously not a very nice guy...
 * I didn't initially support this theory despite actually liking the idea (yeah, I be one of those yaoi fangirls), but as said above... yeah, vol 9 shows Ran to be pretty much a heavy molesting bastard. So while I still doubt it's gonna be canon, it's certainly not OOC on his part - and as a bonus, would also explain why Aoba, despite flirting easily, is uncomfortable when the twins get physical with him. As for pet torture, it's possible too (it is a widespread Freudian Excuse in anime/manga after all), but I don't think Aoba's parents would have let him keep a shark so I'm not gonna follow that one.
 * Original troper here. Found this on the kink meme and it's very disturbing to say the least but the worse part is that it's in character. Make what you will...

Shinra is a Yandere.
Think about it: His first meeting with his future love interest involves cutting her open. He lives with said woman for twenty years- it's implied that over the years he didn't think of anyone other than Celty as a potential love interest- and constantly says she'll be his future wife. He does basically everything in his power to keep her from finding her head, just because if she does she MIGHT leave him. He insists on marriage only, something that would bind her to him through legal means. And he does it all while smiling that creepy little smile.
 * Alternate Character Interpretation indeed!

Izaya is an incarnation of Loki.
Or he deliberately acts like he is, to troll other people with passing knowledge of Norse Mythology and the audience.
 * It's actually Lampshaded by Namie. Izaya shrugs it off, though.

The events of Durarara!! take place in the early timeline of Warhammer 40,000.
Think about it (but not too hard)! Since this would all be occurring on Terra around M2 its reasonable to assume all the weird stuff thats going on Ikebukuro is a result of the still young Chaos gods exerting their influence on a humanity that has not fully awakened to its psychic potential yet. Don't buy it? Look at Anri. Wields a sword, wants to love everybody to death, refers to her followers as "children" and they to her as "mother". She's clearly possessed by a Great Unclean One. Izaya is quite obviously being whispered to by a Lord of Change. And who hates those scheming parakeets more than anything? Just try to tell me Shizuo isn't a mini Khorne berzerker. It all adds up man.

Simon was once forced to eat human flesh in the past
Simon is awfully insistent in making sure everyone knows that there's no human flesh in his sushi. Now the normal conclusion for this sort of thing, considering the setting, would be that he and Dennis have some sort of Sweeney Todd thing going on, but this seems unlikely, given his pacifist nature and status as The Atoner. So why is he so hung up cannibalism?

One possible explanation is that, somewhere in his Dark and Troubled Past, Simon wound up in a Donner Party-esque situation (maybe some secret KGB mission gone wrong) where his options were to eat the flesh of his already dead comrades or starve to death. He came out alive and sane, but was understandably traumatized by having to eat his buddies and is still a bit hung up about it. So, while the fist question that comes to most people's minds when encountering strange food usually isn't "Hey, this Russian sushi doesn't have people in it, does it?" it's the fist question that comes to his mind, which is why he keeps mentioning it.
 * I personally endorse this theory because otherwise, there are some definite Unfortunate Implications about the black guy being a cannibal, and as you say, he and Dennis aren't the type to pull a Sweeney Todd.

Walker is a descendant of Tick/Chic Jefferson from Baccano!
There's already speculation that Walker is part American. And their smiles are just way too similar.
 * Now that you mention it...*looks at Tick, looks at Walker, looks at Tick, looks at Walker*. Hmm, you're probably on to something there. That smile, plus Eyes Always Shut, plus their, er, talent, all in all it's pretty close to becoming head canon.

Celty sucks at lying because she's a Dullahan
Dullahans are Fey. One of the elements of The Fair Folk? They can't lie - except instead of the traditional interpretation, Naritaverse faeries "can't lie" in that they suck royally at it.

Izaya's Past has to do with Shinra
They never explain how Shinra became friends with such a Jerkass. It would also explain why bringing up the incident in middle school shuts Izaya up and knowing Izaya, it must have been REALLY bad to get him to be quiet. In other words, Shinra might hold the key to Izaya's weakness.
 * Proven true, as of volume 8.

Izaya is going to end up killing someone
This troper has a really bad feeling that Izaya is heading in this direction. And what we've gotten from volume 9 so far
 * Wouldn't giving him a living hell be worse? It seems like something Izaya would do, if for no other reason than to rub his face in it.

Izaya is possessed by a Saika counterpart
He claims to love all of humanity like Saika and hurts people because of his "love." His weapon of choice is a knife, and he can do seemingly impossible things with it, like shave a guy's head from yards away. His rampant use of Insane Troll Logic is because an enchanted blade's logic is nothing like human logic. However, unlike with, or even the other characters posessed by Saika, Izaya fully absorbed the blade into his human body and was victim to a Split Personality Takeover. Becoming human and therefore mortal was a shock for an immortal blade, which is why he has such a strong fear of death that he'd come up with such an insane scheme to find an afterlife for himself.
 * Support. Don't forget that he managed to block Saika (and cut Shizuo) with that same dinky knife--despite the fact that Saika has been shown to cut through solid steel like butter.

Shizuo is going to go to Valhalla
That's why Celty is on Earth; she's waiting for him to die. If Shingen hadn't stolen her head and went to Ikebukuro, Shizuo would have ended up in Ireland for reasons he couldn't explain. They're noted to have a strange connection neither of them can explain, but it isn't love. She also fangirls around him when he does really impressive things.

So the series is going to end like this: Izaya will have his war, and will manage to kill Shizuo. Then Celty's head will awaken, and she'll go full Valkyrie. She'll grab Shizuo, ignore Izaya completely, and then promise Shinra she'll come back to him.

Shinra is a closet masochist
Think about it. He doesn't mind getting smacked, punched, slapped, kicked or even freakin' strangled by Celty, and it's even implied that it arouses him. Adding to this, there are times when it seems like he's bugging Shizuo just to goad him into punching him. He also never seems to care when he gets injured. Plus, the idea is really funny.
 * If he's in the closet, it is the most transparent closet ever. There was at least one time he deliberately goaded Celty into Dope Smacking him, and was happy when she did.
 * Shinra is Suzaku?
 * Yes, mai lordo.

Durarara takes place in the near future, where anonymous has become a physical organzation
And goes by... the dollars.

The crime that Izaya framed Shizuo for has to do with taxes or something credit related
It would explain why Shizuo can't hold a proper job anymore and why his younger brother wanted him to keep a steady job so badly. This troper figures that something simple may be too little for Izaya to pull off, but he is a total jerkass and would stoop to petty crime like this to get something done.

主角，Celty Sturluson, 是死神
She carries a scythe and uses it to chop down those she sees fit. 只是尖叫死神
 * It's chinese instead of japanese for comedic effect.
 * That not many people understand...

Yadogiri Jinnai is the manager of Shizuo's debt collection company.
We only know a few things about the manager. In Shizuo's flashback in the novels, the manager gets mentioned as one of the people who isn't scared of Shizuo, and the narration says "He knows how to deal with Shizuo". Right afterwards, it brings up Simon and specifically states that he can protect himself from Shizuo, so it's almost certain that the manager deals with Shizuo in a way besides violence. We know from Jinnai managing Ruri that he knows how to handle unstable people with superhuman power. Another clue comes in the 9th novel when Tom talks to Vorona about Shizuo being late, due to serving as a bodyguard for the manager, who states has plenty of enemies. Who has more enemies than Jinnai? Not to mention just the fact that we haven't had even a name for the manager mentioned, much less an appearance. And this is Narita, where 99% of the cast is a huge badass and/or epic troll. I don't think he'd hold off so long on showing a character that closely connected to Shizuo for no reason.
 * While not entirely impossible this theory is very unlikely. When Shizuo mentioned his manager that knew how to deal with his anger problems, he most probably meant Tom. Besides, Jinnai rather brainwashed Ruri than really dealt with her. It is also implied that Shizuo's and Tom's manager stays in Ikebukuro. And Izaya sent both Kida and Saki somewhere far away to spy on Jinnai. Not to mention that he followed Izaya all the way to Northeastern Japan, just to stab him. Unless Jinnai doesn’t have shape-shifting and teleportation powers, he almost certainly isn’t Shizuo’s main boss.

The Big Bad of the series isn't Izaya, but
Because we all know it's coming...

Mikado will marry Anri.
Not because teach her how to love again, but because she comes to depend on his protection.

Saika is the Soul Embrace, aka Broken Destiny from the Soul Series "purified" of its evil.
Soul Calibur's wielder at the time, probably Mitsurugi was able to defeat Soul Edge for good. In the end Talim (who seemed to be able to purify Soul Edge in her SC 2 ending), Taki (who was trying to destroy the swords), Ivy (for revenge and atone for her sins serving under Nightmare) or Kilik (who can wield a similar Soul Embrace weapon) was able to purify the sword. The purified sword wanted to follow Soul Calibur's agenda of being "the light of humanity" (like in Cassandra's Soul Calibur 4). That is why Saika loves humanity and its flaws wanting to create a perfectly ordered world. In its sealed and weakened state could not freeze the world like it tried to in Siegfried's SC 4 ending. The sword did retain Soul Edge's corruption abilities and knack for weapon creation. From Soul Calibur it kept its subtle powers like healing, no longer thirsting for souls. It made a plan of saving the world by enslavement and its warriors like Shizuo Heiwajima. Just like how Krita Yuga became Soul Calibur, it will awaken to a world already enslaved. Unlike Soul Edge who is destructive it bides its time. Until then it loves humanity, one cut, one slash at a time.

Izaya is the Master.
Because i think it's pretty clear Izaya's not human. He and the Master are both Faux Affably Evil Magnificent/ManipulativeBastard Psychopathic Manchildren with plenty of Foe Yay. After The End Of Time, he fled to Japan and regenerated. Izaya's fear of death could be related to why the master never dies, even when he's supposed to.

Black Butler is related to the Narita-verse somehow.
I've seen a whole bunch of things connecting Durarara!! and Black Butler, such as AMVs and fancomics. While I am aware that these are not canon, Black Butler takes place roughly around the late 1880's, which would leave plenty of time for Baccano! to occur without a hitch, and due to the Fantasy Kitchen Sink of the Narita-verse. Which leads to this...

Izaya is somehow related to Sebastian Michaelis
Seriously, think about it. They look a lot alike (black hair, red-colored eyes); both have serious rivals (Shizuo and Claude), whom they are often paired with in fanfiction; they both have in-universe fangirls; have people close to them that act cold towards them but are actually close to (Namie and Ciel); both are feared; both are Stepford Smilers, and so on...
 * Izaya also shares his birthdate with Sebastian's seiyuu. COINCIDENCE!?. Oh, and not too mention they both have one unlikely friend (Shinra and Agni). They really are quite similar, but he only thing is that Kuro was written three years after DRRR!! started. Plus, a lot of characters in anime have black hair and red eyes to make them look more sinister, and they don't really look alike other than that.

The goth-loli girl that passed by Mikado and Kida in the first episode is Haruhi Suzumiya.
Why the heck not.
 * Okay, so evidence: Durarara!! takes place in 2004. Haruhi Suzumiya begins in 2006, meaning she would be in her 1st year of middle school, plenty of time for her to be in Ikebukuro and go back home. It'd also make sense for her to be into that style, given her out-of-the-ordinary outlook.

Rokujou Chikage from the novels is the son of Firo and Ennis from Baccano!
He got his fashion sense from his parents, his ladies' man attitude from Uncle Claire, and his battle skills from... everybody. How he wound up in Japan leading a biker gang is a bit of a mystery...
 * The Japan part can be explained; he went with Uncle Isaac and Aunt Miria. The biker gang part I'm still not sure of...
 * Jossed by the fact that as recently as 2002, Firo and Ennis still haven't had sex, even on their honeymoon, which itself was years after their marriage.

Izaya is a changeling
Okay, I admit that I got the idea from a fan fic but it explains so much. How he manages to move so fast (remember when he shaved that guy's head?), his attitude towards humanity, the trolling (The Fair Folk have a history of messing with humans for the lulz after all). He may not know that he isn't human but his true nature shows all the same.

Izaya is the Composer of a Game set in Ikebukuro
Vending machines used as projectile weapons? Controlling masses of people for the greater good with eerie red eyes as a side effect? Everything manipulated by a Magnificent Bastard / Jerkass named after a biblical figure? Perhaps all of the events come out of a twisted competition to see which of Joshua and Izaya can most effectively drive the inhabitants of their city to despair...
 * Isaiah 6 records the call of the prophet Isaiah. God sits upon His throne and asks whom He shall send to the people. Isaiah replies, "Here I am, send me!" God, in turn, says that his preaching will make the hearts of the people sluggish, and their ears and eyes dull, so that they will be unreceptive to the prophet's words, and this will continue until the nation is destroyed because of their obstinacy. Perhaps Izaya misunderstood the call of his namesake, so he actively seeks to cause as much despair and destruction as possible, rather than merely telling the truth and letting the people react as they choose.

Meta-WMG The dub decided not to cast Stephane Sheh for Anri because they didn't want to deal with the Actor Allusion results that the fandom would inevitably produce.
Anri falls within Sheh's typecast: teenage girl (or appears to be one) with huge breasts and severe emotional issues resulting in something from eccentricity to insanity. However, since the dub knew they were getting the 12:30 AM Sunday timeslot, they didn't want to be overshadowed by Bleach, so they avoided casting Sheh in order to be taken seriously.

Izaya has Sadistic Personality Disorder
I was reading a Cracked.com article the other day that described the symptoms (long story), and all I could think was "That sounds just like Izaya!" He "loves" humans, and enjoys getting them into all sorts of horrible predicaments because it amuses him. The reason he hates Shizuo so much is because he's the only person Izaya can't screw with, but he makes up for that by pissing him off for the hell of it. Seriously, Izaya is this!
 * He also combines this with Passive-Agressive Personality Disorder
 * This troper can totally see Izaya diagnosed with this but there's one problem.
 * Izaya's a pretty selfish guy, but even someone with anti-social personality disorder can love in their own way. I'm going to assume that based on some research, those with sadistic personality disorder don't just screw with everyone for their own pleasure and that there must be some people that they decide not to screw with, be it for their own form of love or respect. This troper, however, sticks with the theory that Izaya is a (very realistic) sufferer of ASPD, though I don't doubt the SPD theory, either.

Shizuo's agency belongs to Nebula or some other Giant Corporation
Think about it. The agency pays for the repairs caused by Shizuo (which, considering his Hair-Trigger Temper and tendency to destroy everything when angered, is no small amount) but still can afford to pay the employees' salaries (including Shizuo's), and shows no sign of going bankrupt.

There will be an arc focusing on the Seven Deadly Sins.
With everything the series has covered so far, it wouldn't be surprising. In particular:
 * Izaya will be associated with Pride, and his part will feature him attempting to find Celty's head again and focusing once again on instigating Ragnarok so he can find a place to go when he dies.
 * Shizuo will be associated with Wrath and his story will feature him pulling a rage like he's never done before. It will end very, very badly and someone will probably die, launching Shizuo into a Heroic BSOD.
 * Mikado will be associated with Greed and his part will continue the "Dollars purging" he's been doing lately. It will soon result in him crossing the Moral Event Horizon and becoming the true Big Bad of the story.
 * Masaomi will be associated with Sloth, and his part will coincide with the above. Masaomi will see what Mikado has become and fall into complete and utter despair, ultimately giving up all hope.
 * Saika will be associated with Gluttony and her part will feature her attempts at possessing people, through Anri.
 * Shinra will be associated with Lust and his part will be a humorous vignette about him trying and failing to seduce Celty.
 * Namie will be associated with Envy and her part will show her finally snapping and deciding to Murder the Hypotenuse and kill Mika Harima.