Ruby
I'm fair. I always keep my promises, don't I? And perhaps, when all of this is over, you can have him again. I'll set him free, just as he did for me.
Good. Do this for me, Ruby, and I'll get you what you want.
I'm not worried because you love Sam too much. You would never let Dean kill him and that, of course, is if Dean can even muster up the strength to do it himself.