For me, the thing with Anders is similar to the case with Bartrand. Bartrand's mind gets completely taken over by the red lyrium, and he asks Varric to end it and not leave him as he is. Varric wants to call for a healer, but even Anders can't help him. There's nothing that can be done for him but put him out his misery. Keeping him alive, just leaves him suffering, imo. So I kill him. I do the same for Anders. I feel for him and how he tried to help Justice. But at this point, Vengeance has taken him over. I don't think there's anything that can be done for him, and leaving him possessed is just cruel. Plus, at max rivalry, he's asking me to do it.
Same. I absolutely could not let Anders live, especially after seeing his relationship with romanced!Hawke (it's pretty manipulative and abusive
Honestly, the Anders romance creeps me out. It is very manipulative and Anders is extremely obsessed and possessive. I don't know if people who play the romance don't see it or are able to look passed it somehow (I would love some insight on this, so feel free to explain). I wouldn't even flirt with him except that I need the rivalry points in a pro mage diplomatic Hawke playthrough. But that romance is just one huge no. I refuse to touch it.