Hi, everyone! I've decided to start a collection to post my one-shot stories. I hope you like them.

I'm not a very experienced writer, so any suggestion or review would be highly appreciated :)

Cell Background

idea from a Tumblr prompt

When Castle set foot that morning in the homicide floor of the 12th precinct, two coffees in hand, it was like entering a ghost town. The bullpen was practically empty, surely due to the early hour. He couldn't see Kate Beckett anywhere, which, under normal circumstances, would have worried him, or at least disappointed him. But when he spotted her cell phone resting atop her desk, he realized that she couldn't have gone very far.

The absence of the gym bag the detective always kept under the desk gave him a clue on her whereabouts. If Beckett was working out in the gym, that gave him a window of at least ten or fifteen minutes to take advantage of the situation. It wasn't frequent that the detective left her phone behind. Wherever she was, she always had it on and within reach, constantly alert of new developments in her cases. But the rare times she forgot the device, Castle sprinted into action.

Over the last three years, he had managed to prank her several times. The first time he'd messed with her phone, he had changed his own ID photo, so every time he called her, his smirking face would appear on the screen, surrounded by a glittering heart and the words "KB+RC 4EVER." The next time she'd left her phone unattended, he had filled her calendar app with silly reminders and alerts, like "Tell Castle how ruggedly handsome he was today" or "Wear a provocative dress to work tomorrow."

But Castle's favorite, hands down, was the time when he changed all of her ringtones, which had produced a hilarious scene at the precinct when Gates called Beckett by mistake. From her office, the captain was able to hear that the ringtone greeting her call on Kate's phone was the "Imperial March" from Star Wars. Kate still hadn't forgiven Castle for that one.

Thinking quickly of what his newest prank should be, Castle reached for Beckett's phone, setting the tray with the coffees next to her computer. He tapped the phone's home button, and the screen instantly lit up, demanding that he enter the correct password. Beckett thought she was very clever, changing the combination on a regular basis. He felt actually offended by the fact that, after almost four years of shadowing her, Beckett still doubted his observational skills. Castle knew all of her passwords by heart. That might seem semi-stalkery, or at the very least creepy, to someone else. However, to Castle, it was as natural as breathing. It was an ability that came in handy in moments like this one.

Scanning the bullpen to make sure the coast was clear, he typed in the password. His mission was to switch his phone number with Lanie's in her contact list, so when Kate called her friend, she would actually be calling Castle, and vice versa. He figured it wouldn't take long for Beckett to notice the change, but he could have fun in the meantime.

Too busy focusing on the possibilities this prank would entail, Castle almost missed the picture Beckett had selected for the cell phone's background. Almost. What he saw nearly weakened his resolve to tamper with her phone. A picture of the two of them- Kate and him- was displayed proudly on the phone's background. The moment he saw it, his breath hitched in his throat. It was a candid shot of them taken at the Old Haunt, and he realized as he studied it that he had never seen it before. Kate was perched on a stool by the bar, and Castle was standing next to her, his whole body oriented towards her, and his eyes were twinkling with mischief. He didn't notice those details at first, though. The first thing his brain registered was the joy and happiness Kate exuded in the picture. Whoever took it captured Kate in one of her "Castle moments," as he liked to call them. In between a laugh and an eye roll, Kate was clearly amused by whatever Castle was saying. Judging by the way her lips were pursed, the corners of her mouth turned up and her eyes crinkling with laughter, she was trying unsuccessfully to hide her smile. The image showed the kind of intimacy Castle longed for, and it overwhelmed him.

Without thinking about what he was doing, he launched the photo gallery app, scrolling quickly through the rest of the images without looking at them until he found the one he was looking for. The details of the shot revealed that Lanie had been the one to take the picture.

Without missing a beat, he sent the file to his own cell phone. As soon as he was finished, he locked the device and put it down. No sooner had he placed the phone back in its original position on the desk than he heard a voice behind him, barking his name. "Castle!" He flinched, intimidated by the harsh tone in her voice. "What were you doing with my phone?"

He turned around quickly, finding Kate Beckett standing behind him, her hair still damp from the shower and the gym bag hanging from her shoulder.

"Nothing! I didn't do anything this time, I promise!"

"You'd better not have done anything," she answered, clearly unconvinced, as she sat down in her chair and reached out for the coffee he had let on the desk.

Kate took a sip from the cup, glancing at Castle out of the corner of her eye. It was almost as if she was studying him, searching for some sign of what he had done this time. Castle couldn't help the stupid grin that blossomed on his face as he looked back at her. It stayed there for the rest of the day.

Hours later, in the quietness of her apartment, Kate suddenly remembered the phone incident. She hadn't noticed anything weird with the device, but one couldn't be cautious enough when Castle was involved. Worried about what the writer could have done this time, she went through all her contacts-pictures and ringtones included- followed by her calendar and her alarms. But it wasn't until she opened her recent message list that she found out what he had done.

There, on the top of the list, was Castle's name. Kate's heart started pounding furiously when she saw the image attached to the message. She hadn't even thought about her background image when she was searching for clues about what her partner could have tampered with. She knew that it was risky, because it could start a conversation she wasn't ready to have yet, but in the end, she couldn't refrain from sending Castle a text letting him know he had been busted.

Nice pic, right?

His reply made her smile.

It's my new cell background.

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