9x10 Road Trip
Why was Cas in this episode? It’s one of my favorite Cas episodes of the season, but he didn’t practically speaking contribute anything. He wasn’t required for anything in the plot to work. The only thing he really brought that might have been difficult to swing otherwise was the info (which he’d gotten from Samandriel) that Crowley knew a way to dig into angel brains.
The rest? He brought his wheels, since Gadreel had taken the Impala. He interpreted Gadreel’s Enochian words, got his name and told Dean about his background. He burned off Sam’s tattoo so Crowley could possess him. He healed Sam’s wounds from Crowley’s fiddling. None of that was essential, most of it could have been arranged without him.
And yet he was essential to the episode. He was the backbone of the episode. He was there to give Dean emotional support and boy did Dean lean on him. Dean wore his white-and-pink plaid Emotional Maturity & Openness shirt, it was the last time we saw him in it. This was the episode when Cas and Dean came together again after all the break-up drama of the earlier season, told each other everything, asked and gave forgiveness. I’d say this episode brought them closer together than ever. It was a landmark episode for the profound bond/Destiel, whichever you prefer.
Just take the closing scene at the bridge. Plotwise, Cas didn’t need to be there. It was a heavy emotional scene between the brothers. Cas didn’t do or say anything in the scene other than heal Sam, give the brothers privacy to talk, and look worried and heartbroken when Dean left.
He was there because he’s family. Emotional drama between the Winchesters concerns Cas too now. He’s one of them. He was there to take a few steps on the bridge that Dean needs to cross, to stand there bathed in golden light and show Dean the way.