Sam had always known that Dean's bisexuality was a little fucked up, always figured it had something to do with having Dad, with his on-the-move lifestyle, for a role model, but he didn't really connect the dots until he overheard Dean trying to explain to Castiel that sex with other hunters didn't count.
"It's--it's like playing cards or getting really, really drunk after a bad hunt," Dean said. "It's just, you know, bonding. It's how you know the other guy's got your back. It's friendly."
Sam made the mistake of looking up from the laptop to squint disbelievingly at his brother. Castiel caught his eye and said, "Does he use this line on everyone? What is his rate of success?"
"What! No!" Dean protested. "I wasn't hitting on you! You're not a hunter."
"I don't sleep with other hunters," Sam told Cas.
"And nobody likes you, either," Dean said smugly.
"I don't really think it's common practice," Sam went on. "Just Dean practice."
"Dude, whatever," Dean said. "Dad totally did it, too." Like he was carrying on a venerable Winchester tradition.
"Yeah, but Dad didn't try to come off like he was straight, Dean," Sam said.
"What are you talking about?" Dean scoffed. "Of course Dad was straight."
Sam blinked at him. "Dad had sex with other men. Not straight."
"Hunters!" Dean insisted. "Totally doesn't count."
Sam turned to Cas. "In the real world," he said, "straight men don't cement their friendships with gay sex. Unless they're really, really in denial. Don't let Dean confuse you. If a person likes having sex with both men and women, it's not that some of the sex doesn't count, it's that he's bisexual. Okay?"
Cas nodded. "This is more in line with what I have observed," he agreed.
"What about locker room hook-ups?" Dean asked belligerently. "Pro athletes totally team-build with sex."
This was really deeper insight into Dean's sexual rationalizations than Sam had ever wanted. "Dean. Reality and porn. Not the same."
"Oh, come on," Dean said. "How do you explain Dad, then?"
"What do you mean?" Sam said. "He had sex with men. What's there to explain?"
"He had sex with hunters," Dean insisted. "It's not like he was dating them!"
"Oh, you mean his epic string of one-night stands?" Sam asked. "Dad was a deeply dysfunctional human being who couldn't maintain a long-term relationship to save his life, he was so damn scared of losing someone again, like Mom. I swear he picked that fight with Bobby on purpose."
"What are you talking about?" Dean said. "They were fighting about a hunt. Bobby thought Dad was going off half-cocked and wanted to do more research, and Dad said he wasn't gonna sit around the house and let people die."
Sam supposed it was possible to interpret the fight that way if you ignored about half of it. Maybe Dean hadn't heard everything Sam had, or maybe his denial was stronger than his observational skills. "No, Dean. Bobby asked Dad to move in permanently. Dad wasn't having any of it."
"No way," Dean said. He looked weirdly scared. "I mean, Bobby and Dad hooked up, whatever, they were hunter buddies, but they weren't--Dad wasn't--hell, Bobby's not--"
"Yeah, they were," Sam said. "Dean, if Dad sleeping with other hunters was about being buddies and bonding and whatever else you've got it in your head it's all about, then why do you think there's so many hunters out there who wouldn't give Dad the time of day?"
"Because he was kind of an ass?" Dean suggested.
"Yeah, he was," Sam replied. "He sucked at breaking up. He didn't know how to say he was scared of caring too much--that would have been too honest--and he didn't know how to do casual. He really did care too much a lot of the time. So he picked fights until nobody could stand him."
"But that's," Dean said. "No. Come on."
"Bobby's like a second dad to us," Sam said. "You know that. Why do you think that is? It's 'cause he loved Dad."
"No, we were just around, for a while," Dean insisted. "Bobby's was home base for a couple of years. It was just convenient."
"Bobby's was home base because Bobby and Dad were a thing, not the other way around," Sam answered. "Bobby got around a lot of Dad's crap because he's a grumpy bastard and doesn't like to talk about his feelings, so Dad could pretend he wasn't in too deep. But then Bobby asked Dad to stay and it was too much of a declaration for Dad. He got scared, like he always did."
"This is dumb," Dean complained. "You're talking like they were, I dunno, life partners or something."
"Bobby calls us family," Sam said. "You hear him throw that word around with everybody? Think about it."
"You could," Cas ventured. Dean looked at him like he was surprised he was still there, and Sam felt vaguely guilty about airing the dirty laundry. Still, it wasn't like he'd said anything bad--he'd said Dad and Bobby loved each other, as opposed to Dean, who had been telling the angel about meaningless sex. "You could ask Bobby Singer about the relationship," Cas suggested to Dean.
"He won't say anything like Sam's saying, even if it were true," Dean protested. "Bobby's the original Mr. No Chick Flick Moments. Just--no way was he like that with Dad."
"He told me some stuff," Sam said, going back to his laptop. "Get him really drunk and ask him about Christmas of '91 sometime."
There was a long pause during which Dean was undoubtedly counting back in his head. "The amulet? The one Bobby wanted to you to give to Dad that you gave me instead?"
"What about it?" Sam asked, not looking up. If he looked up, he'd crack up, and it was funnier if Dean got there on his own.
"Dude, did you give me a token of their gay love for Christmas?" Dean demanded.
"You gave me a Barbie doll," said Sam smugly. "You totally deserved it."
Castiel pulled the amulet out of his shirt reverently. "Dean. I am honored that you would allow me the use of such an important family heirloom."
Dean looked gobsmacked. "You know I didn't give it to you as a token of my gay love, right?" he asked.
"Yes, Dean," Cas said kindly. "I understand that you are only interested in being friendly."