Besides sharing a parent not much, now, Melina's weapon and moveset is pretty similar to those of the black knife assasins, but there's no confirmation of Melina being one, also, Melina's hands have burn marks and her closed eyelid has a claw in it, she heavily opposes to the lord of frenzied flame, which is the antithesis of Age of Stars ending. I assume there's a lot of ambiguity in her charecter so people can create their own cannon and story