A/N: Repost from tumblr

Disclaimer: I do not own Castle or its dialogue, but all mistakes are mine

3 AM

(Prompt: at end of the chapter)

Kate had the longest day at the precinct today. She was so exhausted that Castle practically had to carry her pathetic, overused body into bed. Even though her husband appeared to be wired, he had laid down with her so she cuddled against his chest.

Kate had thought they were in bed for the night.

Apparently, she was wrong.

Something caused her to jolt awake while her brain was still in a fog. Half asleep, she turned and found Castle's side of the bed was completely empty. Splaying her arm across the sheets, Kate felt nothing but the cool Egyptian cotton.

He'd been gone for awhile.

"Everybody! Yeah! Rock your body…"

You've got to be kidding me.

That was what had woke her up. Castle was revisiting the 90's in his office and she was living in the nightmare.

She'd admit at first she found his love of bubble gum pop music to be quirky and adorable.

At three in the morning?

Not so much.

"Everybody, rock your body right..."

Murder was wrong.

Murder was wrong.

She loved her husband.

She loved her husband.

Kate nearly screamed a groan and threw Castle's pillow over her head to block out the dance party Castle's was having in his office. It didn't make sense. He would write in the middle of the night from time to time, but never once did he wake her up from his solo karaoke.

"Now throw your hands up in the air. And wave them around like you just don't care..."

Okay, so the pillow didn't help. If anything, it amplified her husband's voice. Throwing back the covers, Kate stalked out of their room toward his office.

She nearly choked when she saw him. There was no way she couldn't laugh at the adorable nerd she was married to.

He had his noise cancelling ear buds in and he was dancing around the room in a way that could only be described as 'dreaming he was sixth member of the group'. From what she could remember from the music video that was once a staple of MTV, Castle was mimicking the dance moves perfectly.

"Am I original…Yeah! Am I the only one…Yeah! Am I sexual…"

Castle swayed his hips and jumped around when he finally noticed her standing there.

"Yeah?" she said, finishing the lyric with a giggle.

He froze for a beat but jumped right back into the song with a quick wink.

"Am I everything you need? You better rock your body right!"

The blush that washed over his face when he was caught was gone within seconds. She shook her head and bit back another laugh as he danced toward her.

She was married to him.

He leaned against the doorway next to her and removed the buds.

"Did I wake you?"

"Mmhmm. While those little things cancel the noise for you, but they don't help control the volume of your voice…"

"Or you're just such a big fan of boy bands that you were jealous you were missing my little dance party," he said, as his eyebrows wiggled and he pulled her into his arms.

"Um no. I actually came to remind you that I sleep with a gun," she said, smirking.

"Cruel. I'm sorry for waking you though."

"You're forgiven. Just keep it down, Mr. Pop Star—or I'll add your performance to your fan site."

She moved to her tip toes and pressed a quick kiss against his lips.

"Good night, Ms. Spears," Castle said, as she turned toward their bed. Instantly, she flew back around and glared at him.

"Excuse me?"

"This morning—in the shower. I'm not the only one that needs to work on volume control. It's okay though. Mother, Alexis and I all really enjoyed your rendition of 'Hit Me Baby One More Time'…"

He chuckled as her jaw dropped in embarrassment.

"I hate you," she stated, giggling and walking back to bed.

"Next time, you should perform it with the outfit," he teased, turning back to his desk.

Reaching to the foot of the bed, she flung one of the spare pillows directly at the back of his head.

"Keep dreaming, Babe."

Thanks for reading! I needed to post something happy after last night's episode. My heart hurts.

Prompter anon asking you to fill this one 'I heard you singing backstreet boys at 3am and decided to sing along oops' AU