Finally, to make Bishop a more believable part of the story, we spliced some of Serana's dialogue and created short conversations between her and Bishop to trigger throughout the story. DAWNGUARD Because Skyrim is an open world experience, the Dragonborn can come upon the questline by hearing...
talk to Serana again to become a vampire lord and go to fort dawnguard. Talking to any member there should give you a quest to get a cure - this may also allow innkeepers to give you the right information as well however havn't tried...