While Dean thought this reasoning was seriously stupid, he didn't say anything about it. He'd never been one to walk on eggshells. Not for anybody but Sam, and even then, rarely.
He'd trained him. He'd done it.
Well.
"When was this?" Dean asked, crossing his arms. "For you. How long ago was this?" He paused. "And how did I 'lose' Sam?"
He wanted to hear the actual word. Sam wasn't lost. Sam was dead. Or he was Lucifer. Those were the two possibilities. Because there wasn't a universe that existed in which Dean wouldn't go to the ends of the Earth and beyond to find or save his brother.