AU where cas rebels and falls to earth pre-canon, where he teams up with stanford-era dean as his hunting partner. they end up sleeping together and developing a relationship, despite the fact that dean drops everything to do john winchester's bidding every time he calls -- making cas stay behind out of fear of getting discovered -- and also despite the fact that both of them know there's something inhuman about cas, with dean pointedly not asking and cas just as pointedly not telling. they manage to cobble together a real routine while they're hunting all across the country and falling in love. somehow, they find real happiness.
and then dean goes missing.
he's ostensibly out hunting with his father, but he's not calling cas back to check in like usual, and when cas finally bites the bullet and drives out to the podunk town dean was supposedly investigating, it's obvious that he never made it to his destination. cas has to weigh several competing questions at once while he's panicking:
- did dean just cut dies and drop him, maybe because he's afraid of his dad finding out about their relationship?
- is he in grave danger?
- how does he track dean down, since dean is an expert on vanishing into thin air and covering his tracks?
- who does he talk to for help? it's not like he can ask john. which leaves only one option, really.
so this is how cas ends up at stanford, breaking into sam's apartment to tell him dean's been on a hunting trip and hasn't been home in a few days.