>>19312627>Chaos forces that doesn't go full retarded and start sacrificing the populace for fun.
In my headcanon most are.
The problem here is that Black Library authors are little more than the best of a really abysmal bunch. They just don't have any brains between them really. They can write "Grimbald's chainsword cleaved Ripsplatter the Vile's head from his evil corrupted body." fine enough and mostly that's what people who read 40k fluff want anyway.
Hell that's what I read them for so I'm not judging them, they do one thing well enough.
Expecting a truly deep and thought provoking clash between demi-god masters of all war is not something you're gonna get from these writers. Legion being the case in point.
Alpha Legion were once incredibly well developed characters. They were insurgents, they were the CIA pumped up to a million, rolled in viet-cong and dunked in Ninja juice. In my head canon the Alpha Legion are traitors, they believed in Horus and sought to overthrow the Imperium with him. They saw that the rule of bureaucratic yes-men and administratum clerks as the beginning of a slow decay and decided that they had to stop it.
That's the war they fight now. A war against the crippling inefficiency of the Imperium, they seek to overthrow the stifling decay and replace it with the rule of the Individual. Every Alpha Legionnaire is a force of mayhem wherever he goes. They hide on worlds, befriending the rich and influential, or giving hope to the lost and the damned. They find the niche that's ready to be exploited and use the planets own resources to build cells of acolytes and cultists. Every Alpha Legionnaire is a revolutionary, and a single one uses their own intense knowledge of war and charisma of their presence to will a planet's own population to action, spreading chaos by the lightest touch.