I'd like to warn some people about potential Dawnguard Spoilers to start off.

So... I've acquired Auriels Bow and Serana told me to go to the Dawnguard and speak to Isran, the man I sided with, to ask for some extra swordsman.
Though, I cannot talk to him, because I accepted Serana's offer to become a Vampire Lord.
So now when I approach him with the bow in my hand, he says 'the bow... You have Auriels Bow!'
But when I actualy try speaking to him, he says 'Get out of here, vaul beast!'

I'm kind of in a delimma here, The only way-out I see is curing Vampireism, though what I DONT want to do...

Any tips or something of the same importance?

Cure yourself then go back and try again. After that ask Serana to turn you into a vampire lord again. (you probably wont have any of the perks you unlocked though)

Just cure it, you can get it back. Plus if you were the leader of the vampire hunters and was as paranoid as him I bet you'd do the same.

Not a bug, talk to the other dawnguard members one of them gives you a quest for a cure

Oh realy? I can just go up to her and be like 'make me a vampire?' thats pretty neat!
The perks are farmable, don't realy care with those.

Thanks!