There's a lot that could go wrong. Of course, if Sam never gets his memories back, he'll never know that anything went wrong. When Sam gets back to Heaven, Dean will know and he thinks that might break him. Of course, it would also mean that his brother could continue with a normal Heaven that's actually Heaven for him if he didn't remember Ruby. Dean takes a deep breath, scrubbing at his face while he tries to process that. "And it's a risk you're willing to take?" Dean isn't judging and while the idea of Sam never remembering him scares him he's trying to keep that out of his tone of voice.

Dean nods a little. "So it's a one-time deal. Once you get back, that's it? And you'll let it go?" He's not completely on board, but he's trying to be supportive and wrap his head around it.