So this one has become a sort of two-part one. They were too short to post separately so I've put them together.

Oh! And I've no idea what it is in America, but here in England we call it a babygrow. It's like a onesie for a baby haha

Enjoy!

Hamish giggled as he was swung side to side. John was balancing him along his lap, his head resting on John's knees and his babygrow-clad feet inches from John's stomach. Hamish was gripping his tiny hands around John's thumbs and John was swinging his knees from side to side, loving the tiny giggles that emanated from the baby as he did.

"Do stop that, John. You'll make him sick." Sherlock commented from his armchair, John's laptop was balanced on the top of his knees as he sat in a crouch like always.

"Don't be silly, Sherlock. He's loving it. Just listen to him." John continued and Hamish giggled again, staring happily up at his father with bright blue eyes. "Isn't that right, H? You like it don't you? Yes you do! Sherlock's just being a spoil-sport isn't he?" John tickled Hamish's chin gently. "Yes he is! Yes he is! A big, fat spoil-"

"Must you talk like that?" Sherlock interrupted. "I never knew babies had such sickeningly-admirable talents of reducing a man to talking like he's lost all sense. Really, John. I thought you were a clever man, a doctor. A military doctor." The detective's eyes widened in sarcasm. "Clearly I was mistaken when deducing your capabilities of resisting-"

"Yes. Alright, thank you." John interrupted, slightly offended and definitely annoyed. "I get it."

Sherlock huffed and returned his attention to his laptop.

John watched the man for a moment, stuck his tongue out at him and laughed when Hamish giggled at it. He looked down at his son, realising the baby found it funny, and pointed across the room at Sherlock before sticking his tongue out again. Hamish giggled heartily and John grinned. He put a finger to his lips before pulling the same face again. Hamish laughed this time, a hearty belly laugh that even Sherlock quirked a smile at, eyes still locked on the laptop screen.

John smiled warmly, love for his son beaming through his grin. His eyes crinkled at the corners and he lifted Hamish up to press a kiss to his tiny button nose.

Hamish giggled once before violently bring both hands in sharply to slap John on either side of the face, a wide-mouthed grin still there on his toothless mouth as he did.

This time, Sherlock burst out laughing and had to put the laptop down. John frowned at the baby just inches from his face before his frown transformed into a smile again and he couldn't help but laugh too. He looked over Hamish's shoulder at Sherlock who was clutching his stomach as he laughed, something John had rarely seen him do.

"Hamish...you brilliant child!" Sherlock managed between laughter. He got up off his chair and made his way over to them both, lifting Hamish out of John's hands and resting him on his hip before sticking his tongue out at John instead. Sure enough, it earned the same response from Hamish and the baby giggled at the funny face again.

John waited for Hamish to repeat his actions and shook his head when he didn't.

"Oh yeah, sure. He only slaps me." The doctor rolled his eyes with a smile.

"That's because you talk to him like an idiot, John."

"John is Papa, I am Daddy, yes Hamish?"

The toddler in his arms nodded as Sherlock awkwardly re-adjusted him on his hip. Hamish's light brown curls bounced on his forehead as his father moved him.

"Sherlock, daddy." Sherlock prompted, hoping his son would repeat him.

John had explained now was the best time to introduce to Hamish that his father's had two names, just as a heterosexual couple would start desperately saying 'Mama' and 'Dada' at their child too. Hamish picking it up early would mean he'd grow up already knowing and accepting it, until he was old enough to question it.

"John, Papa."

"Jawn...Pa-pah!" Hamish exclaimed, lifting his toy tractor in triumph at the word 'pah!' and grinning, wide-mouthed, up at Sherlock.

"Yes, good. John is Papa." Sherlock nodded at his son, feeling his leg grow numb and deciding to gently pace the living room of the flat

.
"Sherlock, Daddy." The detective tried again.

"Sh...lawk. Dad-dy." Hamish attempted and Sherlock's eyes filled with warmth for his little boy.

"Very good, Hamish. Now, Papa is the blonde-grey one. Daddy is the dark-not grey one, yes?"

Hamish nodded, though Sherlock knew the boy didn't understand a word of what he was saying. He continued nonetheless.

"Papa likes jumpers and jam. Daddy likes suits and science. Yes, Hamish?"

Hamish's eyes were locked on his toy tractor, his chin jutted out and brow furrowed in concentration, but he nodded all the same.

"Papa is short, sometimes stubborn with just a little bit of an annoying habit of being in control. But we look past that, Hamish. You and I. We look past Papa's little faults because what's more important is that he is here with us and he loves us. Doesn't he? And we love him, Hamish. Do you love Papa?"

Hamish looked up at Sherlock then, his toy tractor seemingly momentarily forgotten about. The curly haired toddler nodded once, his eyes bright, before managing; "Love Papa...and love Dad-dy." Hamish then leant up, stretching in Sherlock's arms to bump a kiss clumsily onto Sherlock's lips.

The detective froze.

He watched as Hamish's attention was immediately back on the tractor. He'd pulled off one of the wheels and was smacking it against the windscreen with some force while humming contently.

It was obvious that Hamish had picked up kissing from having seen others do it. Just like his speech was picked up by copying words he heard others say. There'd been a few instances where he called Sherlock 'git' or 'smar-tarse', leading John to only encourage that he learn their real names sooner. Naturally however, Greg Lestrade had found it rather amusing, clapping the small boy and cheering every time he did it, causing Hamish to beam up at the DI and John's fury to grow.

But as Sherlock stood, still holding his son in his arms, watching him destroy one of his toys, he chuckled too. John had bought him that tractor.

Unbeknownst to Sherlock, the doctor in question was stood just inside the kitchen doorway. And had been for a while, long enough to see the whole ordeal of teaching Hamish to learn their names. He'd beamed with pride for both Sherlock and his son, glowered in annoyance when Sherlock had mentioned him to have 'annoying habits' and almost welled up when Hamish had kissed his father so innocently.

Sherlock continued to bounce Hamish gently, slowly becoming accustomed to working this young new life around his busy work schedule.

John watched from the kitchen, silently happy that Sherlock had managed to settle a little with Hamish around.

God forbid the next time he had a particularly riveting case, mind you.