So now for another idea: Ciaphas Cain: C'Tan. Didn't abuse the Necrons and survived the War In Heaven. The Valhalen 597th wakes him up and he ends up just kinda vibing with them. Or he's Mag'ladroth incognito.
Amberly: So… you're the Commisar?
Cain: Yep.
Amberly: I'm not sure the Commissariat would agree…
Cain:
Sulla: Inquisitor… with all due respect… he did help our regiment unify…
Amberly: He's a Xeno- Frakk it, C'Tan are above my pay grade.
To have it be relevant to the thread:
Canon Cain: So did that mean you don't have to deal with Emili?
C'Tan Cain: I ate her soul, and the souls of her minions. I managed to save the souls of my men.
Warmaster Cain: I accidentally Ascended my Emili… at least she's helping…
Canon Cain: Better you then me.