Dean and John pre-series where they lived together and shared motel rooms. Dean always had a lot of respect for John, so whenever he hooked up with someone, he'd either go to their place or rent themselves a different room. John never had the same consideration though. It was rare, but sometimes he'd find a girl for himself. He'd stumble in and take her right there, next to Dean. Sometimes Dean would walk in on them fucking on his bed, meaning by the end of the night he had to sleep where John had spilled his seed, with the lingering scent of sex and musk on the sheets. Weirdly enough, Dean buried his face deeper into the pillows those nights.
He always pretended to hate it, the noises they made were abnoxious, embarrassing and hookers had the habit of saying ridiculous things which John loved and reciprocated. Dean didn't know that John did it to get a rise out of him, that John never got off because of some prostitute, he got off on the idea of Dean being upset and disgusted. He loved the scrunched nose and pulled lip Dean gave whenever he passed, because he knew better than anyone else it was all an act to hide the fact his son loved it just as much as he did.
Being his father's son, Dean started doing something similar. At bars, Dean would try to pick up as many girls as possible, make out in front of John, and even when John tried to interrupt, insisting they had to go, he'd put a finger up and arrogantly tell him to wait. Made his blood boil at the nerve, and they'd end up having arguments about it, how Dean "didn't respect him" or how much of a "little shit" he was being, because he didn't want to follow instructions anymore, always ending up with them splitting ways for a few days.
Only to reunite and John force Dean to give him the most violent blow job and then repeat...OK bye