Sam watched Dean walk away to talk to Kevin and then looke back up at the sky to watch the angels fall from Heaven. He watched the sight as he ached and hurt all over. He knew he was dog sick, and he couldn't do anything about it. Or risk getting killed. And sacrificed. He didn't want to be anyone's sacrifice. He needed to be here for Dean. His only living family.
Sam didn't know what they were going to do about him or about the new fallen angels. He knew with him now out of commission, Dean was going to have to do it. He knew he was going to have to rely more on Kevin now than on him. He wondered if Cas would be around to help him, but he knew Cas wasn't answering Dean's calls.
Just then Dean came back. "I know why Cas isn't answering my call," Dean said.
"Why?" Sam asked.
"You really must be out of it if this sight doesn't make you wonder," Dean told him.
"He's a fallen angel," Sam realized. "We need to find God."
"Yes," Dean said. "We will, but we don't even know where to look or who he is or what looks like or if he even has a vessel or if he has a vessel." Dean was rumbling, and he knew it; he just couldn't stop himself.
"We'll find him," Sam said.
"We need to," Dean said. "He's the only one I fear that can heal you."