Prompted by anonymous, inspired by FRIENDS. Enjoy!

Warm sun filtered in through the windows in the living room of the loft, making Kaylee's almost-black eyes seem even more brown as they widened whilst her Dad entertained her on the couch. Rick was so enamoured with his four month old daughter as she laid on a cushion in his lap, her wriggling movements making her sparse brunette hair spike up.

"Look at you," Castle cooed as he gently ran his hands up and down the little one's bare stomach, making her legs kick against his blue v-neck shirt, "Look at your big chubby cheeks." He punctuated this by lightly pinching Kaylee's rosy cheeks, her letting out a squeal at the action. "And your big, chunky legs," He caught one of her flailing legs in each hand, which only made her move more. "And your fat little feet that I could just nibble at all day." To prove his point, he leant forward and put her right foot near his mouth and smacked his lips to make an eating sound, provoking another squeak from the baby as her hands flew up to his face, pawing at him. "And your big baby butt."

"I like big butts," He said to himself with a chuckle, seeing how Kaylee's eyes remained ever focused on his and continued, "I like big butts and I cannot lie, you other brothers can't deny, when a girl walks in, with an itty bitty waist," Rick's hands meandered to up once more to poke at her middle, "And a round thing in your face you get-"

The baby girl let out a tiny laugh as bubbles erupted from behind her lips, immediately stopping Rick in his tracks.

"Oh my God, Kay, you're laughing!" He exclaimed as he used the bottom of his sleep shirt to wipe her drool, the smile still present on her face, "You've never done that before! Did Daddy make you laugh, sweet-pea?"

Kaylee giggled once more, flapping her arms around as she did so. Carefully, not to jostle the baby, Castle reached forward to grab his phone that was on the coffee table in front of him and immediately dialled. It was mere seconds before he got an answer.

"Captain Beckett?"

"God, that's still hot." Rick teased as he settled back into the couch.

"What is it, Castle?" Kate asked hurriedly, and he could hear her office chair creak as she sat up, "Is something wrong?"

"No, it's great! She's laughing!" He said proudly with a grin.

"What? Oh my God, let me hear her!" Kate practically squealed.

Rick used the hand that wasn't holding the phone to wrap his hand around their daughter's stomach, tickling her. Though she smiled, and didn't let out another laugh. He tried other tactics, instead moving his fingers under her arms and on the soles of her feet, but she didn't respond except for kicking again.

"She's not laughing anymore." He explained, hearing his wife let out a sigh on the other end of the line.

"I missed it." She said quietly, sounding dejected. Oh, he hadn't meant to make her sad. "The one day I come in for a stupid meeting!" She complained, "I'm coming home now."

For the next few moments, Castle stayed on the call as he heard her rustling around with papers and eventually her heels clacking on the floor at a fast pace as she murmured quick goodbyes to her co-workers.

"What did you do to make her laugh?" Kate piped up as a beep from the background made Rick assume she was in the elevator.

"I… sang to her."

Her voice sounded even more crestfallen, "I sing to her all the time." And oh, how he loved to hear the sweet melody of her voice echo through the loft as she whispered to their daughter, both in the middle of the night and in the light of day.

Her voice cut through his thoughts, "What song did you sing?"

Rick's eyes widened, "Um…"

"Was it one of the classic Disney songs?" She prodded, Castle knowing that Beckett had been singing Disney songs to Kaylee even though she obviously hadn't seen the movies yet.

"Not a Disney song, but some would consider it a classic." He reasoned, rubbing his hand at the back of his neck.

"Castle."

Just the stern tone of voice made him wince slightly.

"The Sir Mix-a-Lot classic." He confessed in a quiet voice.

For a moment, all he heard was the sound of Kate slamming her car door and placing the phone in the hands-free plastic holder.

She finally spoke as she began the drive home, "The only song I know by Sir Mix-a-Lot is…"

Rick scrunched his eyes shut as he waited for her to make the connection.

"You sang to our four month old daughter a song about a guy who likes to have sex with women with giant asses?!" She called out loudly, making Rick incredibly thankful that she wasn't inside the precinct still.

The father glanced down at Kaylee to see that she was giving him a glare that he imagined Kate also had on right now. Uncanny.

"W-Well," He stammered, "It kinda promotes a healthy body image?"

"Castle!" She snapped, "The only thing she's ingesting right now is my breast milk, I don't think she's worried about her body image!" He opened his mouth to attempt another reason, but was interrupted, "Oh God, one day she could ask what the first thing she laughed at was and we're going to have to say it was 'Baby Got Back'!"

"She'll find it funny!" He rebutted.

The dial tone that pierced his ear showed him that Kate didn't find it funny at all.

Later that night, Beckett woke up to hear Kaylee's screaming through the baby monitor. Since Rick had looked after the baby for most of the day, she decided that she would be the one to get up, regretfully leaving the warm covers and shuffling up the stairs.

An hour and a feed later, the girl's screams had diminished into little weeps, but she still wasn't content enough to fall back to sleep.

"Come on, baby," Kate soothed, hooking Kaylee on her hip and using one hand to rub gentle circles on her back, "Time to sleep, huh?"

Kate sat down on the wooden white-painted rocking chair that was situated in the corner of the room, slowly rocking forward and back to attempt to lull her daughter to sleep. The mother began to sing the song that her own Mom used to sing to her at night, the main reason why she loved elephants so much to this day.

"Baby mine, don't you cry. Baby mine, dry your eyes. Rest your head close to my heart, never-"

Suddenly, Kaylee's crying increased, her hands balling into fists and waving around.

"Come on, little one, that's your favourite!" Kate said in an exasperated tone, looking over at the lilac clock on the wall to see that it had already gone past three am.

She sighed heavily and closed her eyes, willing herself to begin.

"I like… big butts and I cannot lie." She whispered quietly, opening her eyes to see that Kaylee's were already wide as she looked up, "You other brothers can't deny," She released another huff of breath, "that when a girl walks in with an itty bitty waist and a round thing in your face you-"

A melodious laugh filled the room.

Kate let out a loud gasp, "Oh, yes!" She laughed along as she started again, this time with enthusiasm, "I like big butts and I cannot lie! You other brothers can't deny!"

Kaylee's laughter continued, with happy squeals interspersed in-between.

"Oh, Kaylee! Baby, you're laughing!" The Mom said happily, bringing the child up to her chest and hugging her tightly.

"Wow."

Kate's head whipped up to the doorway in surprise.

"Captain Beckett." Rick let out, followed by a tsk. "I never would have expected you to sing such an inappropriate song to a baby." He crossed his arms over his bare chest, raising his eyebrows.

"How did you-?" Kate began to ask, before she saw the glowing green light on the baby monitor. Damn it. "I had no choice!" She argued as she stood up to approach her husband.

"No choice?"

"She wouldn't settle down with anything else! She is all about the ass!"

Rick let out a loud guffaw, saying after he settled down, "That's a dollar for the swear jar college fund."

"Maybe we won't need that fund after all." Kate said quietly with a small smile lighting up her tired face.

"Why?"

"You just mentioned college, and now she's asleep." She joked, turning her head to show Rick their baby girl, with her eyes fluttered closed and her mouth hanging open. He grinned at the sight of the little one looking so peaceful, pressing the lightest kiss he could on a wisp of hair, prompting Kate to do the same before she ever so carefully lowered the baby into her crib, covering her in a blanket that Alexis had knitted for her.

She was beginning to stand up straight again when she felt her partner beside her.

"That's okay," He whispered into the shell of her ear, "if she continues to have a big butt, she won't need a college degree to earn money."

The punch Kate gave his arm left a bruise for days.

Thanks for reading, hope you enjoyed! Feedback is always welcomed and very much appreciated.

Lou xo