There were many surprising moments for me, but Cas being blown up by Sam or Lucifer *confused*. It was more startling than anything really. Then Cas coming back, and bringing Bobby back! It was a surprising finale, let’s just say that!
The whole episode was filled with surprises for me. First I was totally surprised that Dean agreed to let Sammy say yes. I mean I knew it was coming but I expected more of a fight first. I was surprised but then not really when Sam didn't win in the battle of taking over Lucifer at the beginning. I had a feeling it was too soon into the episode for it to happen. I was totally surprised and shocked when Cascas blew up. Cried. Then Bobby. Cried harder. Then Cascas came back. Cried tears of joy. And then Bobby came back. Was to worn out of emotion to cry more. lol Then I was shocked Dean didn't try to save Sammy. I was also, even though I am a total Dean fan, mad at Dean for not saving Sammy. He went crazy when Sam died and sold his soul to bring him back but now he just lets Sammy rot in (well is hell the right place or is it like a place that just is and doesn't have a name *owww head hurts*) wherever he is rotting. So yes I was surprised and shocked with the season finale. :D