"And thus the third War of Armageddon was won, the guardsmen and PDF cheered, the surviving civilians were safe, and the M&Ms got humiliated in front of everyone by being slapped by Tushan, chapter master of one of the nicest Space marine chapters ever."
This begs the question though: Who's gene seed spawned these guys? I doubt any of the First Legions would even want to consider these guys as their progeny, but if I had to guess it might be...
1. Dark Angels (MMs might just be taking it too far on the guilt part, though the lack of dark green and such negates this a little)
2. Iron Hands (Believes the weak deserve to suffer, though unlike the MMs the Iron Hands don't go particularly out of their way to hurt civs and allies.)
3. World Eaters (Always angry all the time? I know the World Eaters are traitors, but they might be an offshoot and they are constantly mad.)