"I'm pretty sure you can figure that part out for yourself," Ruby says.

The way she says it implies she believes he's a lot smarter than he looks.

"Think about it. Yellow Eyes killed your mother. Then he made sure every single person your mother knew followed after. He was covering his tracks. And damn good of him, too."

Yeah, there might be a barely noticeable smidgen of admiration there.

(Demon, remember?)