The Lord of Death

What if after The Emperor defeated Sanguinius, he decided to utilize his power to banish the entirety of The Red Tear into The Immaterium, sending it hurtling through The Warp, thought to be torn apart by the tides of Chaos, so that it's gathered heresies and secrets couldn't be plundered.

Yet, after all this time, The Red Tear has changed, developing a spirit of it's own, eternally linked to it's one true master, The Great Angel. So even after Sanguinius has his soul deleted by Big E, the shards and echoes of him survive through his sons, via The Black Rage.

And through this, The Blood Angels find that those of their kin who fall to The Black Rage, prove to be the closest to their lost father. Yet, there is a point even further beyond The Madness, a place where one's spirit finally embraces the spirit of The Lost Angel, and the marine is capable of calling upon The Red Tear, the eternal lair of their Legion, back from the Warp, becoming it's new master.

With this, The Ruler of The Red Tear can call upon his brothers, scattered as they are, to heed his demands, as The Angel Returned, at the helm of their lost capital ship. And The Imperium shakes at the sight of this long lost abomination, dragged back from the pits of hell once more to torment the dominion of men.

The only way to end The Ship is to sever the ties it has to it's current master, The Angel Incarnate. Several times, when The Red Tear has arisen, the Imperium has managed to slay The Angel Incarnate, and send The Red Tear back into oblivion. Yet now, in the 41st Millenium, is rises up again, under the command of a new champion who has proven to master The Black Rage, and embody the long lost father of The IXth.

Once, he was Calistarius, but since his ascension, he has gone by the same name as all who have ruled from the decks of The Red Tear.

Mephiston: Lord of Death.