Title: Brothers and Sisters
Characters: Mycroft, Sherlock, Abby, John
Warnings/Triggers: background and discussion of a character in alcohol withdrawal, and a passing reference to a past addiction, coarse language
Spoilers: Oblique ones for The Reichenbach Fall
Pairings: Background John/Sarah
Summary: Mycroft pays a visit to Baker Street to do some consulting, and finds himself assisting in child-minding.
Author's notes: There have been a few people asking for Mycroft and Abby interaction, and I had several versions of this story, but this is the one that worked the best. It's a bit fluffy, as is my wont.

Set in the Abby 'verse. Abby herself is about two and a half, or a little older.

Other stories in this verse, also uploaded here: Decent Proprosals, Perfect, Otitis Media, Christmas Future, The Voice in Counterpoint.

The door to 221 Baker Street was unlocked when Mycroft arrived. This wasn't entirely unusual; Sherlock, even now, had a sense of invincibility (perhaps even more so, considering what he'd faced and survived), and since John Watson had moved out, there was only Mrs Hudson to make sure the house was secure. Since there was no answer to his ringing of the bell, he assumed she was out.

The child's wellies at the front door suggested that John was in, though.

Well, in any case, it made it quite easy for Mycroft gain access without the usual fight.

He climbed up the familiar stairs to 221B, and found, as he expected to, Abby Watson sitting in the middle of the living room. He did not find John Watson, however, or Sarah Sawyer. Just Sherlock.

"To which branch of the family do I send the condolences?" Mycroft asked, assuming someone must have died for John and Sarah to leave their only child with Sherlock of all people.

"Neither," Sherlock replied. "Well, not yet. Harry Watson is evidently doing her best."

"Ah," Mycroft said. "Yes, it is about time for her usual relapse, isn't it?"

Sherlock shrugged. "I don't keep track," he said. He frowned and looked down at Abby, who was hiding behind the arm of his chair, peering over it to spy on Mycroft.

"Hello," Mycroft tried.

She ducked down behind it.

"Shy, are we?" Mycroft said.

"She's not shy, she just doesn't like you," Sherlock said, with a good deal of glee.

"Perhaps you could reassure her, then," Mycroft suggested.

"Or you could leave," Sherlock said.

"I have a case, if that makes a difference," Mycroft said.

"I'm very busy," Sherlock said, sticking his nose in the air defiantly.

Mycroft's eyes swept the room, gathering the evidence he would need to mount an argument. "You haven't left the flat in three days," he said. "You haven't had a case in four. You've been forced to child mind, and you're bored out of your skull." Mycroft could see that had made a chink in the wall. "You don't have to leave. You just have to look at some files."

"I don't have to do anything," Sherlock retorted. He held out his hand. "What am I looking at?"

Mycroft handed him a mobile phone. "Personnel files," he said. "There is someone in a bureau who is leaking information to the press. We can't find out who without investigation, and don't want to be very overt in investigating, lest the person get tipped-off. Just see if anything flashes out at you. I've looked myself and have my suspicions, but I would like a second opinion, as I'm a bit too close to the situation to be entirely unbiased."

Sherlock took the phone and started to scroll through. Mycroft took a seat in the chair opposite him. Abby once again peeked out at him, and he smiled at her. She give a shy smile back, and disappeared, but crawled out a moment later, and resumed work on a drawing she'd be doing when he arrived.

"What are you drawing?" he asked her.

She looked out at him from the corner of her eyes, her look of suspicion very similar to her father's. She didn't respond, just continued to colour. Sherlock's eyes darted over the files, but showed no signs of enlightenment yet.

After a few minutes of this, one of Abby's crayons rolled away and landed at Mycroft's feet. He used the tip of his umbrella to flick it back to her with a little 'shoom' sound. She snatched it up and hugged it to her chest.

"Do you know your colours?" he asked. "Is that an orange crayon?"

He could see her trying to decide if she should respond. Sherlock's favourite thing to do at her age was correct people, but he wasn't sure if that was universal, or merely a quirk unique to his brother.

She shook her head. Apparently it was universal.

"It's not?" Mycroft said. "What colour is it, then?"

"Blue," she said.

"Oh, I see," Mycroft said. He tapped a different crayon with his umbrella. "Is that orange?"

"Green," Abby corrected.

"Where's the orange one, then?" Mycroft said.

Abby picked up the orange crayon and held it up. "Orange," she said.

"You are a very smart young lady," Mycroft said. He flicked his eyes over to Sherlock, who was staring. "Yes?"

"How do you know how to do that?" Sherlock demanded.

"Do what?" Mycroft said.

Sherlock gestured toward Abby. "Make her like you," he said.

"Well, I do have some experience with small children, Sherlock," Mycroft said.

Sherlock frowned. "Who?"

Mycroft chuckled "I know it's hard to believe, but you were a child once," he said.

"I was never a child," Sherlock said, with a smirk.

"Not for long, no," Mycroft agreed. "But for a few years."

"And I was amused by that?" Sherlock said.

"Oh, yes," Mycroft said. "There was nothing that amused you more than showing off what you knew."

It wasn't any different now, he noted. Sherlock's phone rang before he could respond with the sarcasm which Mycroft could see him winding up to. Sherlock glanced at the name and muttered under his breath.

"John and Sarah have been calling me every fifteen minutes since John dropped her off," he complained, before putting the phone to his ear. "For the love of Christ, I will not kill your child!"

Mycroft could hear John's voice clearly; he was speaking loudly to hear himself over what sounded like a busy hospital. Perhaps A&E, or a particularly full ward.

"You better fucking not," John said. "Is she okay?"

"She's fine, just as fine as she was when your wife rang, and as fine as before that when you rang," Sherlock said. "Do you need me to take a picture as proof?"

"No, sorry, Sherlock," John said. "I didn't realize Sarah was ringing as well. I'm at the A&E now. Harry's...not good. You know each time you go through withdrawal, it's worse. She keeps going cold turkey, so she's got the kindling effect working against her. They're giving her benzos. I'm going to be here for awhile, she's going to have to be admitted. Sorry, you don't care about any of this, I know. I just need-fuck. Okay. So, Sarah thinks she might be able to get there around four, will you be all right until then?"

"Everything is fine," Sherlock said. "And if it were not fine, I would notify someone. She is quite happily playing with Mycroft. She is not dead or ill or sad. It's fine."

"Mycroft is there?" John said. "That's...not reassuring."

"He'll be gone soon," Sherlock said.

"I don't know if that's reassuring either," John said.

"I'm hanging up now," Sherlock said. "Stop ringing."

He ended the call before John could object.

"What has Harry done precisely to warrant all this?" Mycroft asked.

Sherlock's eyes squinted, as though he were struggling to remember. "She came to John's home in hysterics, I believe," he said, after a moment. "Quite badly into the DTs. John felt it wasn't good for Abby to see, and Sarah was at work, so he left her here while he took Harry in."

"I must admit," Mycroft said. "That for all you put me and yourself through during your addiction, I'm grateful that you only did it once."

Sherlock looked as though he were about to say something pettish, but he stopped himself, and just gave a terse nod instead. "Agreed."

He went back to work on the phone. Abby tugged at his trouser leg, and he glanced down with a raised eyebrow. "What?"

"Sher-lock, I draw flower," Abby said, putting the drawing into his hand.

Sherlock held it up to his face. "Daisies don't come in blue," he said, and gave the paper back to her.

She looked puzzled for a moment, then brightened and toddled to the kitchen. Mycroft strained to make sure she wasn't going to brush anything on the table there, but she went around it to the fridge, where she found a magnet and placed her picture there. She clapped her hands. "Pretty flower," she said. "Yay Abby!"

Mycroft and Sherlock both chuckled at that. She toddled back to the living room, and dropped to the floor again. She selected a new piece of paper, and a crayon, getting up once more to bring it to Mycroft.

"You draw flower," she said. "Yellow."

"I'm not very good at flowers," Mycroft said, accepting the paper. "And I prefer charcoal. But, I'll do my best. This will be more of a chartreuse flower, I believe."

"Charchoose?" Abby echoed.

"Yes, chartreuse," Mycroft said, showing her the crayon. "This colour is chartreuse."

Abby peered over the arm of his chair to watch as he sketched out a quick rose.

"Oooh, pretty flower," she said. "Charchoose."

"Thank you," he replied.

"I didn't know you still drew," Sherlock said, craning his neck to look as well.

"I don't," Mycroft said. "But it appears to be similar to the proverbial bicycle. One doesn't forget. Grand-maman would be pleased that one of us inherited the art gene."

"You're hardly doing the Vernet line proud with that," Sherlock said. "It's lopsided."

"It's meant to be," Mycroft said. "Rule of thirds. Also, I'm using a crayon and computer paper. Hardly the best of supplies. Could you play a masterpiece on a poor violin?"

"I could do it better than you're doing that," Sherlock said.

"Would you like to try?" Mycroft said.

"No," Sherlock said.

He went back to the mobile. Mycroft finished off his rose, rather pleased with the results. Abby took it from him and promptly scribbled all over it in a pretence of colouring it in. Sherlock was extremely amused by this. Abby returned the rose to Mycroft, who complimented her and folded it up and placed it in his pocket, feigning great honour at the gift.

"I boots," she said. "I puddles. Spish-spish. I want. You boots?"

"Ah, I'm afraid I didn't bring my wellies," Mycroft said.

"Blow bubbles?" Abby asked.

"And I do not have bubbles," Mycroft said.

"Gamma bubbles," she said. "I go Gamma."

She marched toward the stairwell, and both Mycroft and Sherlock got up to intercept her, Sherlock a bit more quick on his feet. He pulled her back by the hand. Her face flushed red and tears formed in her eyes.

"I want Gamma!" she said.

"Gramma isn't here," Sherlock said. "Sit down."

"No! I want Gamma!" Abby howled. "I no like Sher-lock! Bad!"

Sherlock gave a helpless shrug in the face of this. He turned to appeal to Mycroft, who was no better off than Sherlock. Mummy dealt with tantrums, for the most part. He could only try Father's technique.

"Abigael, that is enough," he said, sternly.

This had no effect whatsoever. Sherlock just stared down at her, as though she were a particularly baffling clue. After a few moments, he tried crouching to her level.

"What is wrong with you?" he asked.

"I want Mummy!" Abby wailed.

"Perhaps she's tired," Mycroft suggested. "You always got very hyper and fussy when you needed to sleep. Does she still nap?"

"I don't know, why would I know that?" Sherlock snapped. "Do you want to sleep, Abby?"

"I want Mummy!" Abby said.

Sherlock picked her up in a sort of desperate motion, and she wrapped her arms around his neck and stuffed her face in his shoulder.

"Lovely," he muttered, with a roll of his eyes. He shifted in place in a gentle rocking motion. "There, there. Go to sleep. Go to sleep."

Abby's cries quieted down, and within a few minutes, she was asleep on Sherlock's shoulder. He put her down on the couch, and she curled into a ball, still sleeping, with her mouth wide open.

"What do I do now?" Sherlock asked Mycroft. "Is that right?"

Mycroft was, to use the vernacular, gobsmacked at the idea that Sherlock might be asking him for advice. He recovered himself quickly, not wanting to discourage the practice. "I don't think there are rules involved, but you could try putting a blanket over her, if she came with one," he said.

"John had a bag..." Sherlock said, looking around.

He found it behind his chair, and rifled through, throwing things out of it left and right. He pulled out a small receiving blanket, something that looked to be Abby's from birth, a bit well-loved. From her maternal grandmother, Mycroft deduced. She had no living paternal one, except for Mrs Hudson as pseudo-grandmother. Mrs Hudson would have knit or crocheted, this was store bought and expensive. A grandmother spoiling a newborn.

Sherlock dropped the blanket on Abby. Mycroft had to grip the arms of his chair to resist the urge to get up and lay it properly. It would do. Sherlock stared at Abby for a few moments, as though he expected her to wake up screaming, and then slowly backed away and returned to his chair.

"Why do you remember all that from when I was a child?" Sherlock demanded. "That can't be useful."

"It was, just now," Mycroft pointed out.

"But, not in every day life," Sherlock argued. "You're hardly putting cabinet ministers and ambassadors down for naps."

"Sometimes I'd like to," Mycroft said, wistfully. Sherlock stared at him, openly curiously, demanding a response. "I don't know, Sherlock. I don't pick and choose my memories as you do. Presumably they stayed with me because I find them meaningful in some way. Good memories, perhaps. Simpler times."

"Boring times, you mean," Sherlock said.

Mycroft smiled. "Same thing."

Sherlock handed him back the mobile. "It's either Drake or Venditti," he said. "Drake can be bought, Venditti is bitter."

That followed Mycroft's thoughts precisely, but he had preferred to have a second opinion on a matter of this severity. "Thank you for your help," he said.

"Watch out for Morrison," Sherlock advised. "She'll be the next to betray you."

"I know," Mycroft said. "She's there so she will. We have to catch her out."

"She's not involved in this, though," Sherlock said.

"No," Mycroft said. "Which is quite vexing."

"She wants power," Sherlock said. "Promote her. She'll do something then."

"I'll consider it," Mycroft said. He stood up, and retrieved his umbrella. "Please give the Sawyer-Watsons my regards, or regrets, whichever appropriate. Enjoy your child-minding."

"With any luck, she'll sleep until Sarah arrives," Sherlock said. "How long did I nap for?"

"On a good day? Ten minutes," Mycroft said, pleasantly.

Sherlock groaned, and Mycroft left, laughing.