Title: The Golden Rule
By: carolinecrane
Fandom: Criminal Minds
Rating: PG
Series: 1) Foundations, 2) House Rules, 3) Synesis
Summary: Derek explores the concept of sense memory. Part four of the Laying Foundations series.

***

There are rules about this sort of thing. As far as the Bureau's concerned this is strictly against the rules, so that one went out the window when Spencer kissed him the first time.

But they've got their own rules too, some they've talked about and some they don't have to, because they're professionals and they know how to keep their relationship separate from their jobs. No touching on the clock is a big one; it just makes sense, because they have to keep their focus sharp when they're working and thinking about the way Spencer's skin feels under his hands isn't likely to help with that.

The trick is to find a balance, because he touched Spencer before -- a hand on his back to steer him in the right direction, a touch on the shoulder when he gets himself wound up a little too tight, a quick tousle of his hair just to see him smooth it back into place -- and if he stops all of a sudden someone's going to notice. It goes with the territory, and J.J.'s already proven how tough it is to keep a relationship secret in their line of work.

So he teases Spencer as much as ever, and Spencer still brings him a cup of coffee when he stops to get his own, but now when Derek's fingers brush his as he takes it, it means...something. And even that's a little too close to the line, but it's no different from before, so unless he wants to give up coffee there's no reason to change it now.

No driving into work together; another rule they don't have to talk about, because there are only so many times they could explain that before somebody caught on. So Derek drives to work alone, straight to the office while Spencer stops off for coffee somewhere, arriving ten minutes later than Derek and carrying two cups.

And they're not spending every night together, so it makes sense. There are nights when Derek leaves work and heads for the gym, when Spencer goes home alone to exercise his brain or do whatever it is he does when he's not sleeping with Derek.

He wonders sometimes what it is that Spencer does on those nights, but when they're alone together he's not thinking about what happens when they're apart. Mostly he's just thinking that they never get enough time, even though they spend more time together than Hotch ever spent with Haley. And he likes working with Spencer, likes watching him put together the pieces of whatever case they're working on, likes bouncing ideas off him and watching for the moment when that spark lights behind Spencer's eyes and Derek knows he's on to something.

But there's a difference between time spent at work and time spent alone, whether they're working on the house they're renovating or heading straight back to Derek's place to mess up the sheets. Those are the times when the rules don't apply, when he can curl a hand around Spencer's waist and pull him in for a kiss. When he doesn't have to worry about who's watching them, and he can spend as much time as he wants just looking.

Not that he hasn't always watched Spencer, but he catches himself at it a lot more these days. Or maybe it's just that he's more aware of it now that he's worried about who else might notice, who might catch him looking and jump to all the right conclusions. So far no one -- at least he doesn't think so, but J.J. probably thought the same thing for a long time -- and he knows he has to keep it that way, because if Hotch finds out one of them is going to get transferred, and he's pretty sure it won't be Spencer.

And Derek wouldn't even blame Hotch, because he knows Spencer's irreplacable. He knows that better than anyone, and that's the reason he's willing to take such a big risk with both their careers. With his heart, and he never would have seen that coming.

He's watching Spencer again, catches himself just in time to look away before Hotch frowns at the two of them and starts asking questions Derek can't answer. Like why, in the middle of trying to find a missing coed, Derek's suddenly so interested in watching Spencer's hands. Derek doesn't have an answer for that one -- not that he'd say to Hotch, anyway -- so he clears his throat and when Spencer looks up at him, he doesn't let himself grin.

They're supposed to be on their way to the girl's dorm, to talk to her roommate and figure out who she hangs out with. And maybe he should try harder to get Hotch to send Prentiss with him instead, but he can't bring himself to give up even a drive across town with Spencer.

"You ready, Pretty Boy?"

And he's called Spencer that a million times, so no one thinks anything of it. Except that when he says it this time, Spencer ducks his head and doesn't quite manage to hide a smile.

It's an effort to stop himself from resting a hand on the small of Spencer's back to guide him out of the police station, and Derek grips the keys of their rental car a little tighter as they cross the parking lot together.

They spent last night in a hotel not far from here, and that's a rule they have talked about. They don't share rooms, and they both know it's not a good idea to spend the night in the same bed while they're working a case. So Derek hasn't even touched Spencer since they left D.C., and when they slide into the car together -- alone for the first time in over twenty-four hours, and he's really losing it if he's counting -- his fingers ache with the memory of the last time they touched. Curled around Spencer's own fingers, sliding down his back, pushing through his hair -- Derek can feel every bit of it all the time, and when he catches himself wondering if he's got some sort of photographic sense memory he laughs.

"What?" Spencer asks, the corners of his mouth turned up in anticipation of the joke.

"Nothing," Derek says, but he smiles at Spencer and starts the car. "You sleep okay last night?"

"Stared at the ceiling most of the night," Spencer answers, but he doesn't look that upset about it. "I have a hard time sleeping in strange places, which is sort of inconvenient, considering how often we have to do it."

Derek bites back the urge to offer to help Spencer out with that problem tonight. For one, there won't even be any sleep until they find their unsub, and anyway, they agreed that it was too dangerous to take that particular risk. Instead he grins as he eases the car into traffic, pointing them toward the university before he glances over at Spencer again.

"You do okay at my place."

Spencer's cheeks flush when Derek's voice drops just a little lower, and Derek's pretty sure that's never going to get old. "That's different."

He doesn't have to ask what Spencer means. Thinks about asking anyway just to see if he can get Spencer to say the words, but instead he just reaches across the seat and rests a hand on Spencer's thigh. Just a touch, a beat or two before he puts his hand back on the wheel where it belongs. But it's enough to deepen Spencer's blush, enough to make him smile in that way that makes him look even younger than he is, and Derek decides that's worth breaking the rules every once in awhile.

***