Written for #FictionFriday on my tumblr with the prompt of "Insides."

Disclaimer: I do not own Supernatural.

Senior year had been a whirlwind- pictures and prom and college acceptance letters (as well as rejection letters) and everyone preparing to leave the nest and take that first wobbly step into adulthood. And then summer came, and it was like everyone was trying to get in their one last hurrah every weekend. People were drunkenly hooking up at parties or starting frivolous, summer romances that were never meant to last or breaking up or making plans to try the long distance thing. But no one was starting real relationships, no one was saying I love you for the first time, and that's where Cas found himself struggling.

Castiel had stayed focused all of his senior year, maintaining the grades he needed to go where he wanted and not have to worry about money in the process. He hadn't graduated valedictorian (that title going to Anna Milton), but he'd still been in the top ten of his class. And in all that time, he'd ignored everything high school romance related. He'd never had time for it then, and figured he would have plenty of time for it later. But now summer was coming to a close, and, with it, all of Castiel's chances he thought he'd saved up. Cas would be leaving for Dartmouth in a few weeks, while Dean would be staying close to Lawrence, and he found himself wondering just why he'd ever thought waiting was a good idea in the first place.

There'd been the obvious of he was too busy with school for a relationship. There'd also been the fear that high school relationships never last, and he'd certainly never wanted to risk his friendship with Dean over something that could fizzle out in just a few short months. But years passed, all of high school, in fact, and never once had Cas found himself doubting his feelings for the other boy, nor did he ever find himself doubting Dean's feelings for him.

Dean had never said anything to him, exactly, but Cas had known Dean almost their whole lives. He saw how Dean treated his girlfriends and even his other friends, and none of it amounted to a tenth of how he treated Castiel. Dean probably thought Cas didn't notice how Dean watched him, but he did, he always had. He was hyper-aware of it by this point. It was a feeling that sent sparks flying under his skin from the sheer intensity of it. He would also call bullshit if Dean ever tried to claim that the way the two of them would share a bed and wake up curled around each other when they stayed over at each other's houses was normal. There was something between them, something profound, but neither had ever pursued it. Cas could guess that for Dean maybe it had something to do with his image or his family or some other thing that Dean was terribly insecure about (not that he would ever admit to any of those insecurities to anyone besides Castiel and Sam). But for Cas... For him is had started for all the reasons he'd already listed. It had been purely rational. And then eventually, as the feelings and the tension between them grew more and more intense, it had more to do with fear. He wasn't exactly sure what he was afraid of, but it was ever present, fluttering along with the butterflies in his stomach whenever Dean would look at him for too long or too intensely.

Prom night had been the nail in the coffin of that fear. They'd been alone together at the after party, both buzzed and happy, high on life and probably a few other things (at least Cas knew he'd been). Their dates had disappeared for the moment, and in all the revelry, they'd almost kissed. At least, Cas was pretty sure they'd almost kissed. It was the only way he could think to explain Dean's hand on his jaw and breath against his lips, while his green eyes had been hooded and gazing down at him in that way they made his stomach twist into pretzel knots. And it was the only way he could think to describe the way his heart raced and his breathing sped up as he leaned into Dean. But then the moment had been broken by Garth stumbling over, throwing his arms over their shoulders, and slurring that everyone was doing keg stands now.

After that, they never acknowledged it. They'd finished up the school year, and when graduation rolled around, they both had separate plans. Dean celebrated with his family, while Cas went out and partied the stress of finals away with friends.

They'd seen each other plenty over the summer, but still never acknowledged the almost-kiss. They spent the months planning the layouts of their dorms with all their other friends, going to movies, partying, discussing their course loads for the fall, and even just laying around playing video games. It was as if nothing had changed, except that when they were alone, the air seemed supercharged now.

And so Cas had agonized. Should he say anything to Dean? Was there even a point to it all by now? And why wasn't Dean saying anything? Did he think Cas wasn't interested (which considering Cas's lack of romantic involvement for the past four years, he couldn't blame Dean if he did think that)? Or was he wondering the same things as Cas? Had they missed their chance?

It was two nights before Cas's flight to New Hampshire, and the whole day had been dedicated to Dean. It was the last time they would see each other for months, and they did everything they could to make the most of it. They went out early for a hike, went to the Roadhouse for lunch and pie, went to see the new Marvel movie that had come out, drove Baby all around Lawrence, and finally had a night of movies and games planned since Cas was staying the night. The day had been perfect, everything Cas could have ever wanted for his last day with Dean and more. They were parked at the lookout, leaning against the impala, watching the summer sun set over the town before they headed back to Dean's house.

When Cas caught Dean's eyes, the blush that crossed the other boy's face told him all he needed to know. He'd caught Dean staring, finally caught him, and as they held eye contact, Cas could clearly see how the evening could play out. He could see himself reaching out for Dean and bringing him in for a kiss. He could see Dean pulling him tightly against him before they both fumbled into the backseat of the car, all hands and lips and messy, teenage passion. It would be fast and needy and probably a little embarrassing. But then they'd fix themselves back up before heading to Dean's, and instead of movies and video games, they would slowly undress each other, properly this time. They'd use the whole night to explore each other to make up for all the time they'd already wasted. They whisper I love you as they joined together that first time, and then they'd whisper it a million times more until morning. When Cas would have to go.

He could see it all play out, and from the look in Dean's eyes, he could see it too, wanted it just as badly as Cas did. But the thought of the next morning, that they only had so many hours left, formed a black hole in the pit of his stomach, and all the butterflies there died. So, instead, he just offered a small smile, saying, "I had a great day, Dean, can't believe it's almost over." And then he looked back out across the city, the sunlight fading quickly to be replaced by the street lights below.

And he heard Dean shift to do the same as he muttered, "Yeah, me neither."

And then they both got in the car and drove to Dean's house where they stayed up all night watching movies because there was no more time for anything to change.

So I'm actually pretty darn happy with this, especially for being an on-the-spot, no prior plotting thing.