Can I still go into Ruunvald as a Volkihar Vampire, even though it is part of the Dawguard Radiant quests? I still want to explore it, but I haven't idea where it's and I don't want to find it if I can't delv into it. If I can, what is there? Is the Dawnguard member still there? Or is he there only on that Quest?

Thanks!

i joined the dawnguard adn i didnt go to ruunvald for a radiant quest

Well, I heard that it was radiant just because it isn't in the main storyline, but I heard that you go there to save a Dawnguard priest of Arkay from warped Vigilants that attack you on sight.

You have to speak to the Breton after recruiting her. Eventually she'll give you a quest to recruit a former priest of Arkay. That's when you will be sent to Ruunvald. Not so much a radiant quest. More of a side quest.