Kanye is long rumored to be g-a-y/bisexual. His lover is allegedly fashion designer, Riccardo Tisci. (google - there are a million links.) Marina and Riccardo are very close, and she sold her NY apartment to him. http://uk.complex.com/style/2013/08/marina-abramovic-facts/she-sold-one-of-her-three-lofts-in-soho-to-givench

Marina is pretty mainstream, if you consider appearing in Sex and the City, mainstream. Her work was famously featured in the episode where Carrie Bradshaw meets 'The Russian'. https://www.youtube.com/watch?v=5JvdsNpkMcU

Marina is nutty as all hell, but I think she's just one of those folk who aspiring hipsters try and associate with in an effort to appear cool. I don't see her eating or trafficking babies.