I've painted up my 'Betrayal at Calth' models as Imperial Fists and Iron Hands... But that of course means the game doesn't really work.
So I made this guy to lead my Iron Hands.
The idea is that when playing the board game, the Fists are the Loyalists, and the Hands have gone bonkers in response to the death of their Primarch; with no idea who to trust they've turned to this prick, who's so obviously evil it's beyond a joke. Of course, they're not in a mentally fit state to judge, what with being so consumed with grief and rage they can't think straight.
Makes things a little more tragic. The Fists have to keep killing men who are still loyal to the Throne, but who won't listen to reason because they can't. Meanwhile, the Moritat is well in thrall to Chaos and is responsible for all the daemonic stuff going off.