Beep

Beckett's middle desk drawer is the only one that is locked. He knows, because he's always been a sneaky snoop and despite the risks involved with creeping through a detective's personal belongings in a police station, he can't help but run his fingers over the items she touches daily - her keyboard, the frame on the corner of the desk, and her nameplate. He used to tell himself it was character development, that by sitting in her chair and touching her things, he could dive into the intricate mind of Detective Kate Beckett.

He's long since given up on that pitiful excuse though. He knows her desk probably better than she does herself, and that knowledge, combined with Beckett's anal-retentive penchant for neatness, has led to the escalation of their unacknowledged outright war. He casually nudges her mug of pens several degrees to the right in order to watch her nostrils flare as she pokes it back into place. He always makes it a point of ignoring her coasters and sets their coffees down on her desk to make two perfect rings of condensation before tracing a curved line to complete the smiley. It doesn't matter how often his tiny actions irk her, it's their secret game that only they know they're playing, and he loves to watch her lips twitch upwards when she plays her hand.

He's snooped through her drawers enough to know that the top one contains pens, pencils, paper clips, extra staples, sticky notes, and a hidden stash of chocolate at the back. And he's almost certain she keeps strict inventory of her candies, because the one time he dared to steal a Reese's cup, he tasted an odd hint of salt in his coffee. He doesn't really want to know how she managed to pull that one off, but he's learned his lesson, and Beckett's chocolates are strictly off limits.

The third drawer is a bit more boring, and as far as he can tell it's filled with old case files and newspaper clippings, all meticulously organized in an alphabetical file system.

It's the middle drawer that fascinates him. This is the one drawer that hasn't yielded to his furiously subtle yanks when Beckett's back is turned, and whatever lies within has remained a mystery to him for several months. Still, he makes it a habit to stroke the handle every time he passes, giving it a gentle pull just to double check it's still locked as he dreams of the day it miraculously springs open into his waiting hands.

The first time it happens, it's a Monday. He's passing by her desk, and his fingers automatically seek out the second drawer handle, tapping it then tugging it when it happens.

Beep.

Startled, he stops stock still in his footsteps, and his forehead wrinkles. He tugs again.

Beep.

Now he's convinced it's coming from the drawer, whatever it is, and he bends down for a closer look. He crouches next to Beckett's desk, stalking the elusive beep, and waiting for it to sound again when he notices two pointy shoes appear right under his nose.

He shoots up in surprise, slamming his head with a sickening thunk on the edge of Beckett's desk and cursing it's wooden stiffness when he realizes whose shoes they are.

"Castle. What the hell are you doing underneath my desk?"

He gives a noncommittal grunt before mumbling something about "dust bunnies" and "cookie crumbs" and hurriedly brushes nonexistent lint off his coat as he quickly sits down in his chair. They get to work on their current case file, but he can't help but steal furtive glances at the desk drawer every couple of seconds.

Just when he's beginning to think it's all been an enormous fragment of his imagination, three days later it happens again. The moment before his fingers hit the handle, it beeps ominously.

Beep.

He glares at the drawer, daring it to beep again, and pokes it hesitantly. When no beep occurs, he boldly touches the handle for a full two seconds.

Beep. Beep.

Is the thing communicating with him? Perhaps a warning, he guesses as Beckett draws near. She plops down on her chair and glances at his empty hands.

"Coffee?"

"Right, right. Just a second."

He's turning to leave, when—Beep. This time he knows Beckett must have heard it. She was right there, listening—but oh, now she's typing furiously at her computer, as if strange alien sounds weren't coming from her drawer.

"Beckett?"

"Hmm?"

"Did you hear that?"

"Hear what?"

"The beep."

"Castle stop being ridiculous and get me my coffee."

Casting a suspicious glance at the drawer, he mutters something along the lines of "cranky" and "caffeine" before wandering off to get Beckett her fix.

He's decided to take up lockpicking. It's one of those handy, often misunderstood practices that's frowned upon, but he figures that if his intentions aren't malicious then technically he's not doing anything wrong. Still, he waits for the lunch break when most of the detectives are out to settle down by Beckett's desk and break out his bobby pin.

Beep.

Now it's just mocking him.

"Shut up!" He whispers at the offending inanimate object, before getting to work on the lock. Several minutes later, as sweat beads his brow, he determines that picking locks isn't as easy as they make it sound.

Beep.

He tries futilely, one last time.

Beep. Beep.

Frustrated, he pulls the bobby pin out and jabs the drawer.

Beep-beep. Beep.

He lightly punches the drawer and winces as his knuckles smart before glaring at it and striding purposefully away.

"I can't hear you." He claps both hands on his ears as he chants in a sing-song voice, stalking toward the elevator even as the drawer continues to sound.

Beep. Beep. Beep. Beep. Beep. Beep. Beep.

He reads an article online about high-pitched ringtones that only teenagers can hear because the tonal range is too high for the average adult. He briefly considers this, before he notices the ad along the side of his browser window warning that excessive LSD use can lead to auditory hallucinations. He entertains the notion that Beckett has been spiking his coffee with LSD, before concluding that he's probably just insane.

The next day, he pouts as Beckett announces that he won't be allowed to ride along with her to pick up a suspect for questioning. His frown droops continually lower, before he realizes that with Beckett gone, he'll be able to search her drawers to his heart's content. As soon as the elevators door close, he's on his feet and pawing through the top of the bottom drawer, trying to figure out if he can somehow jimmy the panel and access the middle drawer through there. When that doesn't work out, he does the same with the top drawer, up until a golden glint catches his eye. He shuffles through a mound of office supplies until he fishes out a small key, about the perfect size for the lock on the middle drawer. His breath catches in his throat before he lets out a distinctly ladylike giggle of glee.

Beep.

"Oh no you didn't" Castle crows as he begins to hum "We Are the Champions".

Swiftly, he brandishes the key and jabs it in the lock, turning it carefully before yanking the drawer open in triumph.

Only to find… nothing. Absolutely nothing. The wooden drawer is a void of emptiness and there isn't a speck of dust inside, much less a secretive beeping object.

"GAHHH!" Castle roars for a moment, then after seeing many officers pause to stare at him strangely, turns it into a great, heaving yawn. He slams the drawer shut and plops down in Beckett's chair, glowering moodily at her desk.

"Ooh, ooh! Me, me!" Detective Ryan raises his hand and jumps up and down in excitement as he whines, "Beckett, please choose me!"

"Please," Detective Esposito muscles Ryan out of the way. "There's an art to this. And I hate to break it to you bro, but clearly I'm the one for the job."

Beckett laughs and fingers the tiny remote in her palm as she peers through the cracks of the breakroom blinds. "Not a chance, boys."

She firmly pushes a button, and a second later Castle springs up from his seat, whipping his head around in confusion as he screams, "NO!"

A/N: Inspired by this: .com/gadgets/electronic/b278/