Word count: 900

Genre: romance, AU

Rating: worksafe-ish

Prompt: dean and cas and sam (deancas or wincestiel your choice) ; idk college au

Sam was pretty sure that Dean would love his History professor. First of all, he was really young for a professor, probably a bit too old for Sam to be thinking the kind of thoughts he found himself falling into during the man's lectures, but the perfect age for Dean. Second of all, he was gorgeous enough to turn the heads of every single person in the school as he walked by.

Somehow, the thought didn't make him feel anything like he'd expected; usually he dealt with Dean's "conquests" by ignoring them; he knew none of the girls (and occasional guy) would keep Dean away from him permanently. Dean and him, they were different. Maybe that was really messed up (Sam figured it probably was), but he didn't care as long as they were both happy.

And seeing as he liked seeing Dean happy, he figured he should introduce him to his professor. Just to see where things went, right?

Step one of the plan: make sure Castiel was more than his professor by the time Dean came around to visit him again.

Sam worked hard on step one for several weeks from the start of the term until the week before Thanksgiving. Castiel was resistant at first, not wanting to spend too much time with a student. Even if the regulations at college wasn't as strictly against teacher-student relationships as high schools (the students were, in this case, legal after all), the faculty frowned upon teachers becoming too close with students from their own classes, seeing as that may give them an unfair advantage.

But Sam was nothing if not stubborn. After having been shot down twice, he finally managed to persuade Castiel to have coffee with him outside school hours. A few weeks later, they'd been to four movies and had dinner together twice, and Sam had managed to get Castiel to promise to come have Thanksgiving dinner with him and Dean. Naturally, he hadn't told Castiel who Dean actually was to him; he rarely relaid their relation to his classmates at Stanford, preferring to let them believe what they wished one they saw the two of them together.

Most of them got it right in one way or another either way.

Sadly, Castiel drew a few more conclusions as well.

He pushed the door to Sam's apartment open in a flurry of tan coat and rage, turning around outside only to push a finger into Sam's face, glaring up at him.

"I don't know what game you and your… whatever he is are playing here, Sam, but I can tell you that I am not interested in being toyed with," he growled, eyes narrowed and intense.

"Dude, no, that's not it!" Sam assured him. "I'm not playing any games, I really just wanted to introduce you to my brother—"

"Your brother?"

"—yes, my brother; I thought the two of you would really like one another. And you would, Castiel, couldn't you tell?"

Castiel lowered his hand, and as the anger dissipated, wariness and hurt took its place.

"Sam," he said. "Sam. I already have someone I like."

"Oh." Sam's face fell. "I'm really sorry, I didn't know. I thought that since we've been spending so much time together—"

"Precisely. I've been spending time with you, Sam. It's you I want."

"Well then you're in luck."

Sam and Cas both turned towards the sound of Dean's voice, finding that he was watching them from the door.

"Excuse me?" Castiel asked uncertainly.

Dean pushed off the door frame, taking a few steps towards the two of them. His entire posture spoke of unwavering confidence and not for the first time, Sam got lost somewhere between the desire of being Dean and wiping that smug look off his face with a kiss.

"You see," Dean said as he came to stand at Sam's side, "me n' Sam here, we're kind of an, hm, two-for-one deal, in the long run. Not that we've ever tried anything more permanent with anyone but each other, but I have a feeling the three of us could become pretty good friends. Or what do you say, Sammy?"

Unable to find his voice, Sam nodded. This wasn't anything they'd ever done before; their entire relationship was built around the ability to keep it all under wraps, hardly even talking about what they meant to each other with each other. The thought that he'd be able to not only keep his brother the way he'd always had him, continue the budding relationship with Castiel, and yet be able to see Dean happy with someone who was actually good enough for him for once was more than Sam had ever hoped for.

His nod came to a halt as he saw the strange look on Castiel's face as he regarded both brothers.

"Cas?" Dean asked slowly. "You okay there, buddy? Need a moment? Or a day? We could get in touch again tomorrow if you wanna sleep on it?"

Castiel cleared his throat.

"Maybe—" he begun, voice even lower than it'd been a moment ago, and that was saying something, seeing as Castiel's voice was always pretty damn deep. "Maybe we should continue this inside."

Sam was already dragging both the other men by the wrists back into his apartment by the time he'd stopped talking.