I think maryann is a maenad- which fits into her love for wild drunken revelry, her penchant for inciting lust and a lack of any inhibition in the people around her. There is also a dark side to her obviously, and she may want Tara and Eggs for some kind of ritual....

I am not sure, but if I had to say something I would say a Shape shifter of some kind. She can also make people do things that they would not do on there own.

I think Maryann is maenad and she attacked Sookie in the wood.