How can you do dawnguard dlc all opening to game seems to make you start working for the dawnguard wont they see your glowy eyes and quest is undoable and dlc broken.

I think you are going to have to get cured first or something. I dont know, I might have to play my Orc who was a vampire before Dawngaurd and see how it works.

Yeah, you have to get cured beforehand, as essentially, you join the Dawnguard first, then betray yourself to the vampires.

Chill out. You can start the Dawnguard questline even if you're a vampire - the first quest is available for all characters. You take Serana home, you choose your side. Then if you stay with the Dawnguard, Isran will ask you to cure yourself - if you stay with Harkon, there's obviously no problem.

As a vampire you join the dawnguard first, escort Serana back to her home and there you will have the choice to join the vampires of stay with the dawnguard. If you stay with the dawnguard you have to get cured.

Its pretty cool, Harkon and Serana will have extra dialogue if your already a vamp.

http://www.youtube.com/watch?v=fpzC_JARUuw

Kidding. But there is extra dialogue presented. Serana explains that she knows you are a vampire, and wondered if her father sent you. Harkon just shrugs you off and says your vampirism is a disease compared to the real deal.