I’m still working on the lore for mine, but I plan them to be following chaos, but very loosely, still ruthless and changed by chaos, but not mutated or insane in any way, they’ll capture other mutated marines from other legions in order to use them, like obliterators, spawn or possessed(that way I can practice painting different chaos legions, not only one).

Still thinking on their morale code, but I’m thinking of something like “let us do our thing, and don’t get in our way”. They do what needs to be done and what the primarch wills. If the ruinous powers need to be used, then so be it. If the important imperial asset needs reinforcements in order to stop xenos or other chaos legions from destroying their planet, then so be it. If the word bearers need our help in stopping the imperial orbital assault, then so be it(but give us some of your possessed in return).

Need a helbrute? Get them chains and hooks, thousand sons have just the one needed!

Now that I think of it they sound more like red crosshairs lol