Title: Obsession

Pairing: Dean/Castiel

Disclaimer: I don't own anything.

Rating: R

Warnings: Use of homopbic slurs

Summary: AU: Castiel is the school librarian and he watches Dean, a teacher, every day. He just wasn't aware that Dean had noticed.

A/N: This is the third and final in a set of interconnected AUs taking place in a high school somewhere. Again, you don't need to read those stories to understand what happens here but it will give you a bit more if you do. Complicated is Adam/Michael (warning for student/teacher) and Hated is Gabriel/Sam.

It's an obsession. Castiel could, if he felt so inclined, number the days since he first saw Dean Winchester and fell in love with him. If it were any other feeling than love then Castiel was certain by now he would be over it. He watches Dean through the library windows as he stacks the books. The man strolls around the grounds as if he owns them, with an easy swagger that tells Castiel he knows just how attractive he is and that he's currently gracing the fantasies of half the teenage girls and a good portion of the boys. He's certainly in the fantasies of one mousy librarian. He supposes it's a good thing that Dean seems to have an aversion to books since he never comes to see Castiel. It's easier that way, letting Castiel just watch him and adore him from afar. He's frightened if they did ever talk then everything he's constructed in his head would fall apart.

During the faculty meetings Castiel keeps his head down. Sometimes Dean talks and when he does he's always passionate about whatever he's talking about whether its budget cuts to his department or how to deal with bullying. Castiel hopes he would be that passionate about everything in his life. He's also always filthy, flecked with bits of paint and streaks of grease from the cars he puts back together with his students and that's why it's better that he stays as an object of Castiel's affections from afar. Castiel likes order and neatness. Dean would simply bring chaos into his world so he needs to stay away. Castiel has systems, he has rules – no talking, no food or drink, no mobile phones; he's so careful with his books and his library and he's careful with himself too. Dean is safer when he's not real.

Dean notices though. He pretends to be obtuse to many things but Castiel knows that he's not been terribly subtle about it and Dean is much sharper than most people give him credit for. He doubts anything will happen because Dean is straight but he will probably be angry. When Dean gets him alone in the staff room, crushing him up against the wall and Castiel can feel where the paintwork is peeling off scratching his back through his shirt he guesses this is when Dean will tell him what he really thinks of him, of Castiel's little obsession with watching him. He expects there will be passion, practically fireworks and he's more than ready to be punched. He's moved into uncharted territory here and he doubts that Dean likes being subjected to objectification by male eyes.

"You're always watching me." Dean says accusingly and Castiel just nods because it's the truth. Denying it would be a lie and do no one any good. "All the time, I look up and you're just there and your eyes…" Castiel knows they are unnerving. Gabriel says he never blinks. Dean's hands are brushing across his face, possibly mapping out where he's going to hit him and Castiel closes his eyes for a moment, letting Dean's fingers ghost over them and maybe Dean will give him a black eye. "No, keep them open." Dean says and Castiel does what he's told, opening his eyes again to look up at Dean's face. "I like the way you look at me. Like you need me. Like you're dying of thirst or something and you have to drink me all in." He closes whatever space is left between them and forces his mouth roughly against Castiel's, claiming him and whatever resistance Castiel would have mustered is quickly overwhelmed.

There is a sofa in the teachers' lounge. It's old and it creaks and the springs are starting to poke up through the upholstery. Crowley suggests every year that they buy a new one, something in leather but whatever remains of their end of term funds goes on a booze for the annual "Thank god, three months without those little bastards" party. When Dean is fucking him on it and the whole thing groans and shifts along with Castiel at every thrust Castiel knows that this year he will side with Crowley on the proper use of school funds and demand a new sofa.

Even as he thinks that he expects this to simply be a onetime thing. Dean has an image to uphold. He's so fucking macho that sometimes it hurts. He seems to know however that Castiel would never ask anything of him, that he can get whatever he wants from the other man and Castiel will go along with it so that's what he does. Castiel is still pretty sure Dean goes on dates, that he takes women home but he knows that Friday nights Dean will be staying late, getting everything put away before the weekend and he likes it if Castiel drops by before he leaves for the night. Normally it ends up with Dean leaning back against whatever hunk of twisted up metal is students are trying to make into a real car with Castiel on his knees in the dirt and the oil, Dean's cock in his mouth and the musky smell of Dean all around him. He watches Dean the whole time he sucks him off and Dean says that's the part he likes best.

After one of these sessions Dean is oddly nervous. "I'm having a party on the weekend." He says, shrugging his shoulders like it's nothing. "Most of the staff is coming. You can come too, if you want." Castiel doesn't go out very often. He isn't sure where Dean lives. He'll ask Michael because he knows Michael has been there before, sometimes he and Dean watch a big game together. "I'll come." He promises and tries not to read anything into Dean's smile.

The Saturday rolls around and Castiel isn't sure what he expected but he did not expect to stand outside in the Winchester's back garden while Dean incinerated meat and ignored him in favour of his other guests. Castiel is good with intertextuality, reading between the lines into what authors hint at but never say. He'd begun to think he'd cracked the code of Dean but it turns out that he has simply latched on to a pipe dream theory. If he'd tried to support it with evidence in an academic paper he'd be laughed at. Simply because Dean likes a warm hole to put his cock in doesn't mean he wants anything else from Castiel. Michael is there and Castiel tries to talk to him for a while but eventually he disappears. Castiel calls him, worried he's sick since he left the party so quickly but he gets no reply. Gabriel and Dean are drinking, Sam is somewhere inside trying to make a salad so the food everyone has isn't simply red meat. Castiel feels sick himself and goes home.

He's off work for a week. Most likely food poisoning from Dean's cooking says Gabriel when he comes by with medicine and chicken soup and an infuriating way of wiggling his eyebrows that makes Castiel think Gabriel knows just what of Dean's Castiel has been swallowing. He should get tested, he thinks a bit later to him when he finally drags himself out of bed to make a cup of coffee – black, no sugar. He and Dean have never used protection. Castiel knows he's clean. He could count the number of sexual partners he's hand on one hand but he doesn't know about Dean. "I think I've just got what Michael has." He says when he phones his brother later and for the next three minutes Gabriel makes this odd sound as if he's trying to laugh but has swallowed a fly in the process. Castiel waits patiently until it's over. "Oh, I think you'd know if you had what Michael has." Gabriel says finally and the words just drip with smut. Castiel wishes him good night and hangs up. His coffee has gone cold.

When he comes back to work he resolves to put Dean behind him. He stays in the library. He has an office there where he can eat lunch and if someone needs find him then they can find him there. He'll break this dependency on Dean. He even picks up the newspaper on the way to work one morning and begins circling other jobs he could apply for. He likes his job here, likes the work but he's so weak and if Dean snapped his fingers then Castiel knows he would come running. It's just lucky that Dean never comes to the library. For the first two or three days Castiel hopes that he'll appear in the doorway, like a scene from a movie but eventually that little flame of hope burns out.

As it turns out though Dean is traditional. He waits for Friday. When he comes in he's filthy and Castiel has to come out of his office because otherwise he's going to get dirt all over the books and they're too precious for that.

"You haven't spoken to me in two weeks." Dean says accusingly and Castiel avoids his eye. "You don't come see me anymore, you don't look at me. Did I do something wrong, Cas?"

The nickname hurts. It's so familiar and hints at some sort of shared history but all they've got is sex.

"No, you didn't do anything wrong. " Castiel says with a sigh. "I did. I couldn't just let it be. I…I'm in love with you, Dean. I should never have let it get this far, I have to stop now." He knows Dean will understand now. He'll be disgusted but he'll understand.

"So what? We're stopping because you love me?" Dean doesn't sound disgusted, more puzzled. "I'd say that was a good reason to keep going."

Castiel makes a strangled noise in the back of his throat and finally looks up to meet Dean's eye. "Why are you being so cruel to me? You can't do this to me. I'm in love with you. It hurts me, all of the things we do, they hurt me because I know this is just some light relief to you. I want to stop now, Dean. I can't…" His voice breaks and Castiel has to look away because Dean looks so angry now, like he wants to punch something and that something might well be Castiel. Maybe what he's saying his finally getting through to Dean. Castiel isn't just in love with his cock or whatever Dean's imagining to get himself off. Castiel is in love with him. The real Dean, the one he wanted to stay away from because he knew if he played with fire like this he was going to get burnt. It was all Dean's fault. Castiel was happy to stay away from him, happy to just live with the fantasy in his head but Dean had to find him and make it a reality and now Castiel feels like he'll die if he has to go another day without Dean realising what's happening between them.

"Fuck." Dean snarls. "You think I was…what? That I just thought I had some tame queer to suck my cock? Cas, man, didn't I tell you that first time?" He closes the distance between them and cups Castiel's face in his hands again. "I like you. I don't know how you did it but you got under my skin and now it's like this itch I can't scratch unless I'm with you. Only time I feel good is when I've got you there."

"Oh." Castiel says because it's really the only thing to say. Dean kisses him to shut him up which is probably a good thing.

They break a lot of Castiel's rules that night. There's noise, mostly moaning and most of it Castiel is ashamed to say is from himself. Dean gets grease everywhere, again mostly on Castiel but there's a fair amount on the books from where they rutted up against them, using the shelf for leverage and eventually Dean fishes his mobile out of his jacket and calls home to tell Sam not to wait up for him.

"You're straight." Castiel says a little later as they walk towards Dean's car, Dean's jacket slung around his shoulders and he's interrupted the flow of whatever Dean was saying about how he'd restored his baby from scrap and how she purred now. Dean raises an eyebrow at him and shoots him a grin. "Whatever gave you that idea?" He asks, opening the car door and Castiel can honestly say he doesn't know apart from Castiel knows that would be just his luck, to fall in love with someone so unreachable but maybe that's simply the fake Dean. The real one wants him and Castiel wants him too. They drive back to Castiel's apartment, Dean has something loud on the radio and Castiel's knees feel weak, his body aches all over and he's stretched, he can still feel where Dean was inside him and he's wet from it. Cataloguing all the things Dean has done to him simply makes him hard again.

Reality, he thinks as they draw up outside his home, is far, far better than anything he could ever have imagined.