Sam, Dean, and Castiel were never known for making very rational decisions. Sure, they've saved the worlds more times than one could count but still when the times were desperate, they were willing to go to great lengths. Like working with people... things... that they killed.

They knew it was wrong and it'd probably come to bite them back in the ass once things were over but they decided to cross that bridge when they got to it. The problem at hand was the priority.

"I still think it's a bad idea." Dean shook his head, folding his arms across his chest.

"Yes. We got that the first ten times you said that." Sam scoffed. "It's not like we've got another choice in this."

"Sam's right." Cas huffed. "We get one shot at this and we can't miss it. We need help."

"That kind of help?!" Dean said sarcastically, still not okay with the idea.

Cas pressed his lips into a thin line and replied with, "Yes, Dean. 'That' kind of help."

"Let's just go through with this. It'll be fine." Sam said, trying to stay positive. "Hopefully."