Low-heeled footsteps tracked across the tiled entry and through the hardwood-floored kitchen, echoing against oak cabinet doors and calling out the dark and empty spaces behind: slipping up the wool-carpeted stair, rattling the picture frames against the wall.

Pressed to the eyepiece of his microscope, he pecked at a keyboard with one hand.

"It's been two weeks. Why didn't you answer the phone?"

"I'm fine."

"Well, I'm not."

Sherlock drew his head back. A small woman stood before him in the second-floor laboratory. Large eyes, (dark blue like the sea on a fair winter morning, like her father's favorite jumper) soft features, entirely unassuming and perfectly camouflaged to blend into dull suburban London. She stepped forward and buried her hot face in his shoulder.

He cupped the base of her skull. The weight of worry sank from her vertebrae into the palm of his hand.

"Catherine," he said into her hair.

"I thought - God, I thought - don't you ever do that to me again!"

"Yes, Dr. Watson."

She laughed into his dressing-gowned shoulder. (Tearstained silk, salt precipitating into fractal patterns.) "Please just return my calls next time, will you? Packet of ears in the post? Anything, Sherlock."

"I was busy."

She stood behind him, chin lightly on his left shoulder, wrapping her arms around him like she had in Baker Street when she climbed the back of his lab stool to investigate. "What are you working on?"

"A restaurant poisoning. Thought it was a stupid case of bacterial contamination, but I've found a trace of venom. Isolating it now."

"That's fun. Anything on for tea?"

"Not especially."

Catherine released him and sat on her father's lab stool. A book of crossword puzzles lay on the bench close at hand, open to the last clue John had noted down.

"The very last one. It was wrong."

Catherine held out both hands. Was she begging him to stop talking or merely asking to be touched?

Her fingers wound together with his. "Come and stay with us, Sherlock. I'd feel so much better knowing you were close by."

"You don't really want me to say yes."

Catherine's eyes flicked away for just half a second, enough of a tell. "I can't see you anywhere else but here, but I so hate the idea of you being alone."

Thirty-seven years ago, Sherlock had gotten on a plane. Catherine bulged forward from her mother's belly into a time in which she did not yet exist: baby girl Watson, an unknown quantity. And then -

"I never thought I would get to know you."

Catherine's arms curled tight around Sherlock like a python on a baby baboon. He had never been any good at comfort.

Just stop bloody running your mouth and hold her, idiot. That's all she needs.

Those were John's words the first time Sherlock had cared for the tiny bald thing while he and Mary went out. Catherine howled for the best part of an hour. Mrs. Hudson was away; Molly and Lestrade weren't answering his texts. He was desperate and halfway to phoning Mummy when the tomato-faced creature let out a frothy belch and immediately fell asleep. Midnight found them both snoring in the armchair with Graham Norton blaring in the background. How John (and Mary) loved to tell that story, inventing new and embarrassing levels of detail every few years.

"I know you don't like big emotional to-dos," snuffled Catherine.

Sherlock found himself smiling. "Thought you weren't too keen on them either."

"Motherhood makes you soppy."

So does not-quite-fatherhood.

"Nigel and the boys are out in the car."

"Go get them."

"I don't want to leave you."

"I'll hardly fade away in five minutes."

Car doors slammed, children giggled. They swarmed up the stairs, the baby's bare feet and hands padding doglike on the wooden floor in the hall.

Grandsons, Will and John. Son-in-law chasing after them, wary as always of the sharp and poisonous, the stinging and hot.

"Show me," said Will, tugging at the belt from Sherlock's dressing gown. "Show me what's on your scope."

Sherlock grinned. "It's rather nasty. Are you sure?"

"Hurrah!"

"He didn't get that from anywhere in particular," said Catherine.

Nigel huffed. "Nowhere at all."

Author's Note: Cross-posted to A03. My followers for Patient Doe would probably rather see some happy John & Sherlock AU action than this, but I had to get it out of the way before I could work on anything else. (also to the detriment of the original novel I am trying to finish - heh.) Damn, I hate TV shows that make me care so much about the characters. *shakes fist at Moftiss*

The title is a nod to Coldplay's "The Scientist." I'm thinking about this as the first entry in a drabble series written in reverse chronological order. This is meant to be a little bit open-ended. The Watson-Holmes family as I left them here have begun writing their own back stories in my head. Whether it stays canon-compliant remains to be seen, but we should be good for another year before S4, right?

Thanks for reading. Constructive criticism is always welcomed on my stories. (Un-beta-read and un-Britpicked thus far - unvarnished feels, straight up!)