Dean goes to crash Sam's wedding because he found something shitty about Sam's fiance and is trying to save his baby brother
But he crashes the wrong wedding
"Don't do it! She's not who you want!" Dean yells the second he kicks open the Chappelle doors
Castiel doesn't wanna marry so and so, has been trying to get out of this arraigned bullshit for years
Sees a crazy dude crash his wedding and literally jumps at the opportunity. Doesn't think, just looks at his dad all "He's right father. She's not. I'm gay for that man!" Really awkwardly then runs to Dean, puts all his faith into this and jumps into his arms
Dean has no fucking idea what he just did, but the guards are behind him and now the groom in his arms is going "Run! Run! Run!"
And now Dean is running to his Impala, stuffing Castiel in it, and speeding away with him because fuck his life
And now Castiel is stuck in a road trip to save this random guy's brother from a sham marriage