I love the idea of setting up a necromancer as a class, even if we don't really get classes in the game.
I think that given the things that Larian wants to do with dynamic multi-player story being driven by player decisions, a relationship between an undead party member and a necromancer has a lot of master/servant and animosity built in. You could balance the inherent hatred with a bit of synergy between different class setups.
This way MP trolling actually makes some amount of narrative sense as well.
Just an idea, and I love playing necromancer so just a bit of plugging my fave class
What do you guys think?