Whoa why would you want that
Molag Bal is sixy. Have you heard his voice? Sounds like your typical Daedric jerk.
One of these days I swear I'm going to have a dream with Serana. I dreamt I was Molag Bal chasing a blond woman away from her car in a modern city. No lie! Haha. It is sad, really.
But I do not understand why fans would complain about Serana being "touched" by Bal. She's a vampire. She can heal physically. Though the ego is bruised deeper than the flesh, I suppose.