Lelouch is killed by the Black Knights after being revealed and mysteriously ends up in the Soul Society where he becomes and rises up as a Shinigami of the Gotei 13. Based from R2 Episode 19 and the events leading up to and from the Turn Back the Pendulum Arc.
The Zero Requiem is complete, now Lelouch passes on, fulfilling his destiny. Or has he. Forced into a new world, he shall take up the Mantle of Zero once more, to fix a broken world. (Rewrite of Zero's Remnant)
A new life. Reborn in a world of devils and chess-themed intrigue. After sacrificing everything for a peaceful world, was a Demon Emperor being granted his own personal heaven?