Code Geass 50K: Lelouch of the Imperium

A long crossover fanfiction by Soraga, Code Geass 50K: Lelouch of the Imperium is to Code Geass what Shinji and Warhammer40K is to Neon Genesis Evangelion, melding the series into the bleak world of Warhammer 40000, albeit with a dash of The Shape of the Nightmare to Come.

Set in the even more grimdark future of the 51st Millennium, the Imperium of Man is on its last legs as the the forces of Chaos move ever closer to Terra. Its once mighty power now reduced to a mere shadow and the Golden Throne itself breaking down, all humanity could do it seems is to delay the inevitable coming of Abaddon's Black Crusade. That is, until hope springs from the Emperor's forgotten soldiers: the Black Knights, its immortal leaders bracing themselves for a day they've spent countless generations preparing for. But meanwhile, the once-great being formerly known as Lelouch Lamperouge struggles to stay alive against the machinations of both Tzeentch and the growing insanity of the Warp...

Currently comprised of 34 chapters (35 if one counts the prologue), the Fusion Fic manages to mix the two series almost seamlessly. Noteworthy as well are the efforts put in not only showing ridiculous attention to detail but also adding surprises in the mix relating to both source materials while staying true to canon (except for a few key points relevant to the plot).


 * The Aesthetics of Technology: Deliberately invoked, with the Black Knights' sleek, highly efficient technology shown as decidedly more advanced than the familiar bulky, techno-gothic trappings of the Imperium. Justified in part due to the Knights having retained much if not all of the progress made during the Dark Age of Technology.
 * Ancient Conspiracy: The Black Knights had come a long way from its origins in the anime, with much of its existence prior to the Warp exile largely in the shadows, keeping watch over humanity's evolving civilization. While within the Imperium itself, scattered secrets left behind by Lelouch and barely understood by even the High Lords of Terra are coming to the fore.
 * And I Must Scream: The Emperor, just as in canon.
 * Anti-Hero: Lelouch/The Emperor, although he clearly if privately didn't like some of more questionable deeds done in his time.
 * Bio Augmentation: The are revealed to be a genetically modified subspecies that emerged under Lelouch's watch during the Dark Age of Technology. The fragmented records of their development were later on used to create the Primarchs and Space Marines, though some of the details were mentioned as having been made up from scratch to replicate the original results.
 * Crapsack World: Is it ever?
 * Culture Clash: Between the Imperials and Knights. Made more explicit by the Knights apparently preserving Earth's records and cultures much more accurately and retaining much from the Dark Age of Technology.
 * Death Seeker: It's speculated by the Guardian that a part of the Emperor considers both his internment in the Golden Throne and the warped Crapsack World that his Imperium ultimately became as punishment for his sins.
 * I Did What I Had To Do: It's shown in the flashbacks that the Emperor really didn't like some of the acts he and his Imperium committed prior to the Horus Heresy, wishing at times to rather avoid them if he could help it. This is tied however to the Xanatos Speed Chess he's playing against the Chaos Gods.
 * Downer Beginning: Chronologically-wise. In the distant past, it's revealed that Zero Requiem . Thousands of years later, there's also Lelouch/The Emperor's Imperium sliding into the grimdark mess people know and love...only to slide into further misery by the 51st Millennium.
 * During the War: The fic takes place towards the tail end of one very long one.
 * Enemy Mine/We ARE Struggling Together!: The growing power of Chaos was what motivated the weakening Imperium to drop its "kill Xenos on sight" policy and side with the Eldar and Tau. It's about as stable and trustworthy as one would expect as said aliens had apparently left the Imperials to their deaths.
 * Fusion Fic: The fic is a melding of both Code Geass and Warhammer 40000, with the end result being virtually seamless. Geass-users are also suggested to be a kind of Psyker who could access the powers of the Warp with relative ease and control.
 * Future Imperfect:
 * An appendix reveals that many of the Space Marines' features and abilities were reverse-engineered from fragments of data relating to the creation, though some fragments were less complete than others. The Astartes' ability to absorb knowledge by consuming flesh was taken from a heavily corrupted science log...which conveniently left out the bit on the mere notion as an affront to nature. The Black Knights themselves actively try to avert this, which is reflected in their names, designations and traditions, as a result knowing more about the past than the Imperials.
 * The events of the anime itself are long shrouded in myth, if not outright forgotten by the 51st Millennium. Although the Adeptus Mechanicus and High Lords of Terra have at least a dim idea of what happened in the distant past.
 * Gambit Roulette: Lelouch/The Emperor made quite a few contingencies for the Imperium. Though another example involves CC leaving behind an STC containing codes that would allow the Black Knights to communicate with the Imperials should they return, certain that no one would bother to change the frequencies in that time.
 * Godzilla Threshold: Even if the Imperium at large was unaware of it at first, the Black Knights effectively serve as this, which is at least partly Lelouch's plan all along.
 * How We Got Here: There are flashbacks stretching to the events just after Zero Requiem that slowly explain how things got the way they are in the 51st Millennium.
 * The Masquerade: How the Inquisition attempts to deal with the Knights initially. Sightings and reports are passed off as either STC discoveries or Tau/Eldar/etc. attacks. It breaks entirely when decide to pay the Inquisition a visit...and subsequently manage to put it and the Grey Knights in their place by simply talking.
 * Mini-Mecha: The Knightmare Frames used by the Black Knights have much more in common with Tau Battlesuits (to the point of almost being Powered Armor given how they're roughly as tall as a Space Marine) than their distant ancestors shown in the anime, though they retain many vestigial elements that would have been familiar to Lelouch back in the day.
 * Secret War: It turns out that the Black Knights' leaders have been involved in a long, covert war in the Warp.
 * Time Abyss: The Black Knights' self-imposed exile in the Warp is implied to be this (over 20,000 years in hiding). Their immortal leaders on the other hand are even more so, recalling the events of the anime and the original Knights under Zero.
 * Took a Level In Badass: On the 40K side of things, Abaddon's Black Crusade, which like Abaddon himself is often treated mockingly in fandom, has not only succeeded but is by the start of the fic on a direct course to Terra itself. And then you've got the Black Knights themselves, who have thousands of years' worth of experience by this point.
 * Used Future: Considerably more so than before. Many of the Imperial Navy's more "recent" ships for instance look much more ramshackle and hastily assembled than the ones fielded in the 41st Millennium.
 * Vestigial Empire: The Imperium by the 51st Millennium has largely been reduced to Segmentum Solar and scattered remnants of its once vast territories. Manpower and resources have increasingly become a luxury, with the dwindling armies of Guardsmen and Space Marines falling back ever closer to Terra and the High Lords for once uncertain about their dominions' very survival.
 * The Worf Effect: The Ultramarines are forced to subject their home system to Exteminatus in the first chapter, which goes a long way in showing just how desperate things have become for the Imperium.