John Watson had gotten exactly two hours worth of sleep. That was when the screaming started. The screaming, and the sobbing, and the throwing of small items. It had been three hours now, he could not get Rosie to settle down, and he had to be up in a few hours for the surgery. And later he had his first appointment with another new therapist, this one approved by Mycroft as not being a psychopathic lost relative ahead of time.

He frantically went through everything he and Rosie had done through the night in his mind, desperate to think of what he may have missed. He had tried stories, but the voices he'd put on had made Rosie cry more. The teething rings lay melting on the floor where Rosie had chucked them. John had flipped though every station on the radio, where Rosie'd almost fallen asleep to a dramatic reading of 'The Hobbit', but started screaming again when Smaug woke up. That had been followed by an attempt at a puppet act with some stuffed animals, but they hadn't gotten very far. That had led to pacing next to the window, humming off-tune, and listening to blood-curdling screeches.

There was only one thing for it. He'd have to make a call.

John had been weighing the phone in his hand, trying to make his mind up. It was like on that game show, where you had to phone a friend for help, and you only had one shot at it. Mrs. Hudson was, of course, deep in sleep and truly monstrous when woken up. Molly had pulled a weeks' worth of graveyard shifts to cover for a colleague. Greg, whose experience with his own kids had been invaluable, was at a conference in Leeds. Mycroft was, in this situation, totally useless.

There was only one person he could call, then.

John kept fumbling with the phone. Sherlock usually stayed up all hours, either completely oblivious to the time or hyper and jittery, so there was little risk of him actually being asleep. But, still, there was something that deeply bothered John about needing to call Sherlock Holmes, of all people, for advice on how to care for his daughter.

Just then Rosie let out a particularly desperate sounding wail and he made up his mind. John set the phone on the changing table and turned on the speaker. Three, four, five times the phone rang, and John had almost given up, resigned to a few more hours of wailing, when suddenly the line clicked on.

"What?"

"Sherlock? Am I bothering you?"

Rosie hiccuped in his ear and started sniffling loudly.

"What? No...What's wrong with Rosie?"

"She's teething, Sherlock, and she won't sleep. She needs to sleep, I need to sleep. She always sleeps when she's at Baker Street, so I need you to tell me what you do so I can do it."

There was silence for a long moment, then Sherlock cleared his throat. "I don't...We don't do anything special. Well, we play Deductions."

"Deductions?"

"Yes, with her toys. Would you like to know which stuffed animal was made by a boat-obsessed, hermaphroditic cat owning, leather fetishist?"

John shook his head at the phone while Rosie wiped her face on his shoulder. "What...No. Just...I should start making deductions?"

"Don't be absurd. All three of us know how appalling your 'deductions' are."

"Then what..."

"I think I know now what to do."

There was a scuffling noise as Sherlock switched over to speaker phone and rummaged around the flat. Rosie didn't like the quiet and broke it by crying as loud as she could. Eventually, there was a twanging noise, as Sherlock tuned his violin.

"This one is her favorite."

There started a floaty melody. It was familiar to John but he couldn't place it. It was clearly a waltz, and he began dancing with Rosie, who had instantly settled down. She was very nearly asleep and halfway through their first father-daughter dance before John recognized the tune.

It was the piece that Sherlock had written for the wedding. John swayed to a stop and Rosie drooled into his jumper. He stared at the wall, remembering dancing with Mary, not all that long ago.

The music drifted to an end, and Sherlock stopped playing. "Did it work?"

He didn't quite whisper, but it was close. John set Rosie as carefully as he possibly could in the crib. He picked up the phone, switched it off speaker, and very quietly pulled the door to.

"Yeah. It worked."