So, as I'm sure most of you know, Vampires in TES gets different powers dependant of which bloodline it belongs to. What I'm wondering is, which bloodlines would fit the description of the ones in the Dawnguard trailer? I'm thinking that they might be The Glenmoril Wyrd vampires from High Rock. They are said to be able to blend into society quite well (like The Order) but other than that, we don't know much about them. They could also have a fortress of the Northern coast of High Rock, which would probably have similar weather to Winterhold, much like what we saw in the trailer.
Anyone else have any ideas? I really hope that Bethesda uses a bloodline thats already in the lore, and don't just pull something new out of their asses.