You know never thought of what Vivian wouldn't try to flirt with. I mean anything that wasn't seen as a elf was either a potential slave or enemy to the drow. Surface elves being a deep hated race of course.
As for Vivian. She is just trying to find someone she can get close to. Seeing as the people that she thought was close to pretty much back stabbed her.
Alex on the other hand... Anything can happen with him. Going to let what relationships with him build up.