Azrael

Azrael is Supreme Grand Master of the Dark Angels, Keeper of the Truth, and the man who holds keys the rest of the Unforgiven are not allowed to ask about. He leads the hunt for the Fallen while pretending the hunt is only a rumour.

He crossed the Rubicon Primaris, stood with Grimnar at the Cadian Gate, and was nearly overrun on Wyrmwood before Dante and the Lion arrived. The Rock is his fortress and his prison. Caliban's dust is still in its bones.

The Lion is awake. That should have simplified the secret. It has not. Azrael's job is still to keep the Chapter's shame from becoming the Imperium's schism.