How would one get one over on Molag Bal during the quest The House of Horrors? Seems you've got little choice but to go along with his plans other than to break the quest, which doesn't seem all that great an option and makes your character seem like a murderer. It might be quite approriate given what he's the Prince of but still, how do I do that quest as a good character? I don't want that Vigilant of Stendarr in Markarth forever.

Considering that killing the Vigilant is an act of self-defense, it isn't murder, or evil.

Also, you can kill Logrolf, and break the quest that way, the dude is a daedra worshiper, and evil himself, so killing him would be good.

I don't think a good character would even do that quest.

There are 4 Evil Daedra, Molag Bal being one of them.

I see this question all the time and I never understand it. Why do you need to do this quest at all if you're playing a good character? Why not refuse to do it entirely? If you want the Vigilant gone, just start the quest, get to the point where you kill him (in self defense) then refuse to aid Molag Bal and go about your day.