Well, once you get past the whole spikey in bed thing, and the whole constantly prank scaring you cause he's the lord of terror thing, and the whole thing where he sometimes just... you know, gets down on all fours and runs around like a dog thing, and the thing where he shoots lightning and fire and generally just, you know, even dying won't save you from him, he's actually a really sensitive, thoughtful, and caring guy.
I mean, I've dated all three of the prime evils and let me tell you, "Lord of Hatred" should really be called "Lord of Petty Little Snide Remarks" because god damn I have never seen a more passive aggressive little shit. Oh, you're not as powerful as your brothers and you constantly get farmed by people wearing 1100% MF. Cry me a fucking river.
And Baal? Let's just say... I took his position into consideration, and his terms were not acceptable.
And don't even get me started on Andariel.