>>25045104
I recall seeing somewhere, not sure if it was legit or just /tg/ brainstorming, that he is a cannon character.
His encounters with Chaos have left him horribly traumatized, suffering from all sorts of PTSD and the like, but partly because of that, and partly because I mean really, he has got to be blessed by Khorne at this point he's still a hell of a fighter. Thus the Etherals keep him in a safe place with pleasant distractions until something big comes up, and then they throw him at it like an inaccurate Terminator and pick him up once the dust settles.