Random 40k Fluff

Well, all the Primarchs were tainted by Chaos when they were shot into it as babies. Examples of taint: Sanguinius had wings, Magnus was a cyclops. That's why I said I didn't believe Chaos had anything to do with Lion's betrayal, he was just being a self-serving bastard. And I think he attacked Caliban with such anger because of Luther's personal betrayal.

And alot of characters in the Imperium had tried to fight Chaos with Chaos. It doesn't usually end well, but it happens.

Take inquisitors for example. Always ends badly. I guess you might be right though, simply, because i can't find a way to prove it outside of a gut feeling.