» Tue Nov 20, 2012 3:08 pm
All my vamp playthroughs I was already a vampire before meeting Harkon. Didn't have a single problem. Never got attacked or anything by visiting the Dawnguard at first. Actually, you get some funny dialogue where Isran says something along the lines of "This fort is such a ruin even a vampire could walk right in." I'm not too sure if you can get that dialogue while not a vampire.
But for the first quest, just starting out, the Dawnguard won't attack you as a vampire. They only attack if you side with Harkon.