Muiri. She knows her way around poisons and I would be turn on by someone wanting to marry me after doing a murderous deed. With enough magical instruction, we could... perhaps I should save that for a fanfic.
If not her, Serana the Boss Nord. She is already dead thus she can only ride and she is a master necromancer; you cannot find such splendor anywhere. Throw in the family issues and you will have a "damn romance novel".
What can I say? Ardency is what I am about.