Okay, so here's the thing. I started off intending to play the good guy. But I've blundered into just about every evil daedra quest, couldn't resist completing them, and now i'm wondering around in Ebony Plate (with the Ebony Male), Molag Bal's Mace, the Ebony Blade, and a seriously scary rep.

However, I want to get back on the good guy path for dawnguard. Are there any good quests to promote a change of heart for this guy? Or should I just play Vampire Lord this go-around?

Well, if you haven't done the Companions questline, you could go through that and cleanse your heart of the daedric beast that's apparently infected it at the end, but honestly, I'd just keep him evil. You've got a dark heart and done some dark deeds, and that's not something the citizens of Skyrim will soon forget.

As a way to RP that you're turning your life around, why not do that Temple Quest in Whiterun where you restore the tree. The connotations for taking something corrupted and purifying it again would be a really nice stand-in to RP your character's change of heart.

Just go see Danica (I think that's her name...), and your road to redemption may just begin.

Personally, I like my naughty Vampire Assassin's, so I'll stick with the Dark Side.