yes, one clan is hostile to another and to non clan vampires.

Yeah, but some of the guilds aren't too friendly with eachother as well, and i can still join each and everyone of them. You can bet your ass there's a plugin outthere that allows you to join all three of em.

B_Part , you say you can only get Marara's ring through a vampire quest but i got it early in my game and i was never a vampire.

You don't have to become a vampire to get the ring. you'll probably encounter it during one of your fighter guild quest.

Sorry I got confused: you can get Marara's ring through a vampire quest, but I was referring to Fathasa's ring. Fathasa, Marara, too many alike names... sorry.

However if you retrieve Marara's ring as a vampire, you will make one of the greatest vampires of Vvardenfell happy. He wishes to die by the hands of one of his kin.