Kalin of High Rock
Faal Lun Vahdin
Stephanie Meyer once again has humanised vampires and made them into sympathetic characters... Bollocks! Kill the lot of 'em... Not Serana though, she can be cured so I've heard
The undead have their uses.... but need to be disposed of once you're finished using them, keep it tidy, people.
As for Serana, the way to cure her is to not pester her about it until after the main Dawnguard quest is complete. If you bother her prematurely she'll stonewall on the topic and that's that.