Sam was most definitely an asshole. Not caring could do that to a person.
He knew full well that Dean could be damn stubborn about whatever came out of a creature's mouth. Vampires, demons, whatever. If their lips were moving, chances were that his brother wouldn't buy it.
Although... Lestat did have a point. Dean was screwing a freaking comic book character after all. He had worked with Batman-that had to be a pretty big thing to just overcome.
If this Dean was in fact from a time when he'd known about Sam's soul-and Sam strongly suspected he was-then it was a lot more likely that he might, might just believe.
Sam stopped at the door and turned around again. He drew in a breath.
"I'll bleed into a cup, but you're not feeding from my neck."