Nausea Fuel: Many of the punishments Harry inflicts on the Death Eaters.
Ron the Death Eater: Harry himself as a sadistic undead killing machine. Harry also describes Dumbledore as "the lightest dark lord in history."
Draco attempts to rape Luna and has no issues firing the Killing Curse, something his canon self would likely not have been capable of doing. He and Lucius are both much more willing than their canon counterparts would be to kill each other to save their own skins.
In this story, Stan Shunpike joined the Death Eaters of his own free will.