Mycroft looked over at his sulking child on the side of him. He knew it was rare he had even an hour of free time. He had set aside the day for Artemis, knowing it had been at least a month he spent time with him. He ran his hand gently through Artemis's hair, knowing he would have to work back into his good graces. Artemis let out a loud huff at his touch and clutched his mobile in his hands.

His little boy was not happy with him. He wouldn't spare him a glance, more focused on staring at the floor. Mycroft knew it had not been fair to promise the day at the club with how his job ran. Taking his own mobile into his hands, he typed out a quick message. Artemis had ignored his taps on the shoulder to get his attention.

"I promise to make it up to you, Artemis."

Artemis opened the message and read it with a quick glance. He wiggled further into his seat with a louder huff.

"Promised." Artemis said, his voice raspy and soft.

Ah. He made a note to clear a few days if he could. Artemis rarely spoke unless he wanted to get his point across. The little boy was self conscious of how people looked at him when he spoke. He spoke clear enough to be understood most days, but his words muddled sometimes. He decided to send off another text.

"That I did, but it is an important meeting that I cannot miss. You'll have fun with Doctor Watson and Sherlock."

"I don't like Sherlock. He's mean to Da. :(."

That was nothing new. Children disliked Sherlock on his attitude alone. Sherlock held the same sentiment. He heard about the kitchen incident last week. Sherlock was generally indifferent or downright vicious if he put his mind to it (which was all the time). He let his hand drift to Artemis's shoulder and gave it a comforting squeeze. He would be fine.

John was a better choice in Mycroft's opinion. He would be able to distract Sherlock's prying that he knew would have to be dealt with.

"You will be fine. Doctor Watson is friendly and you can ignore my brother if you like. He is technically your uncle after all." He looked up as they stopped in front of Baker Street. "Don't worry."

Artemis read the text before looking at Mycroft. He huffed and leaned into his side. Mycroft hid a faint smile as he led him out the car. Artemis grabbed his hand in a firm hold as they walked up to the door. Standing on his tiptoes, Artemis rang the doorbell. He smiled at at Mycroft and tightened his other hand on his backpack. They didn't have to wait long as John opened the door. He looked at Mycroft and then to Artemis who he gave a warm smile.

"Hello, you usually don't drop by so early." John said with a look on his face.

It either was the 'oh god what the hell did Sherlock do now' or 'I don't know what is happening but be polite' face. He motioned for them to come in, leading the way up. As they entered, Sherlock was at the kitchen table doing unsavory things to a severed hand. He didn't bother to look at them, focused on the hand.

"Go away, Mycroft. I'm busy."

"Contrary to what you think, I'm not here for you." Mycroft said as he blocked Artemis's vision of the kitchen.

That made Sherlock look up. He saw Artemis who looked less than happy to be in the flat. He must have figured out something by the face he made.

"No. Get out."

Mycroft fought the urge to roll his eyes. He ignored Sherlock and turned his attention back to John. Sherlock would be the last person that he would ask to babysit. He and Artemis did not getting along. Not to mention that Lestrade would have his head if Sherlock managed to upset their youngest son.

"John, would you mind watching Artemis the rest of the day for me?"

John, who had been listening to the conversation, looked surprised. He wasn't expecting that. He was also curious as of how Lestrade's son ended up with Mycroft in the first. The boy seemed content leaning on Mycroft's side, looking around the flat. It wasn't like he could say no. How bad could it be?

"Um, sure? He can stay. Who is gonna pick him up?"John asked.

"Lestrade, if a case does not delay him or I will collect him later tonight." Mycroft said as he tapped Artemis on the shoulder.

Artemis turned from looking at the skull to Mycroft's face. He watched his hands before giving a nod. He hugged Mycroft tight around the waist; the man gave him a pat on the head in return. Mycroft pulled away and left without another word. That left the two adults with a child they barely spoken to. John wondered how exactly they were going to communicate when neither he nor Sherlock knew BSL. The answer solved itself when he felt a tug on his sleeve.

"Hi, Mr. Watson. If you need to get my attention, you have to tap me. We can text each other if you like instead."

John smiled as Artemis held out his mobile for him to answer on. He seemed like such a sweet kid. He didn't believe the stories Sherlock told him about the kid being rude. John heard about the kitchen incident in full detail from Lestrade. Though it didn't explain how Mycroft had Lestrade's son. He would leave that potential minefield alone for the moment.

"Sure. Would you like anything to drink? Eat?"

Artemis read the message and shook his head with a smile. He put in the number John left on his mobile, heading to the sofa. He sat down and scooted his butt until he was in the corner. Taking off his shoes and backpack, the little boy curled up on he couch. He took a tablet out his backpack and started to entertain himself.

John chuckled and headed into the kitchen to start making sandwiches for later. Sherlock was still doing horrible things to the hand so he avoided the table. Digging in the fridge to get deli meats, he nearly dropped what he had. Sherlock was standing behind him. John emptied his hands and put one to his chest.

"Jesus, Sherlock! I told you to stop doing that."

Sherlock waved him off like usual. He watched John prepare sandwiches with a frown. He spared a glance at the child barely filling out his side of the couch. Artemis must have felt his gaze as he looked up to stare right back at him. He stuck his tongue out at him. Sherlock narrowed his eyes and turned his attention back to John.

"You're fine. Why did you tell Mycroft that child could stay?" Sherlock asked.

John rolled his eyes. "Because your brother never asked us to do something that wasn't government related. This was a personal favor though I have no clue why Mycroft of all people had Lestrade's kid."

"He and Lestrade have been in a relationship for a number of years." Sherlock watched as John accidentally cut himself and swore. "I assumed that you knew."

"Of course not! Lestrade always talks about his divorce!" John snapped as he looked for a plaster.

"Mycroft keeps his personal relationships secret. Most likely the child's full last name is Lestrade-Holmes. At least, that's what Felix's last name is."

John gave Sherlock his 'I'm not impressed' look at the information. He was going to have words with Lestrade at the withheld information. Sticking a plaster on, he wrapped up the finished sandwiches and put them back in the fridge. He poked Sherlock hard in the chest as he turned back to him. It was like dealing with a child. Even the actual child they were minding wasn't as bad as Sherlock.

"His name is Artemis, Sherlock. If you can remember his older brother's name, especially with the messes you two make, you can remember his. Especially since you're his uncle if he's Mycroft's son." John said as he went back into the living room.

He walked to the sofa and sat by Artemis's side, startling him for a second. John only smiled as Artemis handed him the tablet he was playing on, looking at what was written. The two ignored Sherlock and started to have a conversation through typing on the tablet. Sherlock was not amused. He didn't want to bother with a child that obviously adored Mycroft. Who in their right mind liked Mycroft? In his mind, it was near impossible. He turned back to his experiment and started to clean up the space.

He rather not hear John bothering him about the cleanliness of the kitchen table again. As he placed the hand in a sealed container, Sherlock thought about what John said. Being an uncle was a strange thought. He had no reference as both his parents were from households where they were the only child. He knew that Lestrade had children from a previous marriage but he thought they lived with the mother. The only vague memory he had of said children was a few years back.

Lestrade put him up for a few days before he was able to get the flat at Baker Street. He remembered a teenaged Felix forcing food on him and the fire department being called. There had been no other child at the time.

He finished cleaning up and looked into the living room again. Artemis was making signs with his hands and John was poorly mimicking it. He disliked children, but at least the child on the couch was quiet. If he was indeed Mycroft's son (oh how he couldn't wait to tell on him), he would most likely be into more intellectual pursuits. It would be easy even though he knew Artemis didn't like him for some reason.

Making a decision, Sherlock went into the living room. He sat on the coffee table in front of Artemis. He ignored the questioning look John gave him as Artemis turned to look at him.

"I imagine that text and BSL are your main ways communicating. Do you read lips? Speak?" he asked.

Artemis stared at him with a curious look before he gave a nod. It was obvious he was trying to figure out the detective's reason for the questions.

"I speak sometimes. I don't like to. It's hard."he said, clearly uncomfortable and trying to keep himself from being too loud.

Sherlock wasn't bothered by the speech pattern. He could see why people would be uncomfortable with it. He saw no reason as without hearing, Artemis couldn't hear the vowels he needed to pronounce the words right. He thought about how to broach the next topic.

"I know that your Mycroft's...son. I believe by now he has told you I'm his brother which makes me your uncle."

Artemis raised an eyebrow at the words. He nodded before opening his mouth to speak. He made a few sounds, but seemed frustrated on what to say. Typing on his tablet, he pulled it close so neither man could peek at his words. When he finally finished, he flipped it so it could be read.

"Papa told me before, but he said I could ignore you if you were too mean. I don't like you much since your always mean to Da. He works hard as a DI and you just like being rude and a show off when you help him."

John couldn't stop the laugh that came out his mouth. He covered it to muffle the giggles as Sherlock glared at him. It was hilarious. Sherlock looked ready to hit him so he went to the kitchen to make tea. It was no sense in the word a retreat for safety.

Sherlock watched John go with an annoyed look. There was no reason to laugh at him. Especially when it wasn't his fault that Lestrade could be an idiot on the job. He would never say that he was the least idiotic of the lot after all. But, he wanted to experiment with the idea of being an uncle.

"How about we make a deal? We'll start out with a clean slate. I want to experiment with being your uncle. We can pick three things to do and you have the option of veto at least once." He said.

Artemis looked surprised and just a tiny bit happy. His Da didn't have siblings and his mother only had sisters. He always wondered what having an uncle would be like. He typed on the tablet again.

"It's a deal. Can I call you Uncle Sherlock?"

Sherlock made a face. "No. Just call me by my name."

His new nephew grinned and made an effort to speak his name aloud. It came out somewhat jumbled, but Sherlock knew he was trying. It sent a strange warm feeling through his chest. It was horrifying. To his luck, John came with a tray of tea for them to share. He handed Sherlock his own before placing the tray on the coffee table beside him. Artemis ignored the tea for tugging John's sleeve and typing on the tablet for him. John stopped preparing his own tea to look at the screen. Whatever it said made John look up at Sherlock with a warm smile.

"That's great, Artemis. I bet Uncle Sherlock would love doing things with you. I bet you want to do something together today, right?" he replied.

Artemis nodded and clapped his hands together. Sherlock was not expecting that. He raised an eyebrow at John since the man didn't include himself in the 'doing things'. John shrugged his shoulders and ruffled Artemis's hair as he stood, making him giggle.

"I have to go to work. I'm trusting you to not get into any trouble babysitting. Mycroft will get you killed or deported out the country if anything happens to his son." he said as he grabbed his coat.

"We already came to an agreement and you made food if he gets hungry-" He let out a sigh at the look John threw his way. "If we get hungry."

John nodded and said his goodbyes as he headed down the stairs. He heard Sherlock ask Artemis what he wanted to do. Sherlock was taking his uncle thing seriously. What could happen in the span of a few hours?

It turns out that John was wrong. Apparently, a lot of horrible, no good, disaster laden things could happen. He almost bumped into Mycroft's back as he went up to the flat. The man looked like he wasn't going to step one foot inside. So, John peeked over his shoulder to see what havoc Sherlock created. He found his mouth opening in shock at the state of the living room.

The furniture was tipped over and made into barricades on both sides of the room. What could only be flour was sprinkled all over everything and there was a distinct white haze in the air. The sounds of something bubbling over the kitchen could faintly be heard. Nasty pink slime was dripped and dangled from the ceiling. John could hear Artemis giggling and watched him peek out from the space under the upturned sofa. The little boy was covered in flour head to toe and the slime coated his hair.

He held Billy in his arms and seemed to be looking for Sherlock. The detective had a water gun in his hands and was hiding behind his own upturned armchair. The slime coated Sherlock more than Artemis to the point it dripped from his clothes as he knelt. Both had distinctive rings around their face, no doubt from the safety goggles they had around their necks. Sherlock probably noticed Mycroft once he stepped foot into the building, but was ignoring him.

Sherlock waited until Artemis wiggled himself out all the way before standing. He walked forward and sprayed him with the same slime that dripped from the ceiling. Artemis squealed in surprise as he got hit in the chest and pulled the skull up in front of him for protection.

That must have been all Mycroft could take as he cleared his throat. Sherlock dropped the gun on the floor and tapped Artemis on the head. He giggled at Sherlock and followed his motion to finally see Mycroft. He beamed at him and took a step forward, slipping in a puddle of slime. Sherlock steadied him with a hand on his back before could fall. He finally realized his state of being and the smile turned to one that looked more home on his brother's face.

"Dare I ask what you have doing and what substance is covering my son?" Mycroft asked.

Sherlock shrugged and started to sign with his hands. He must have been doing a horrible job since Artemis laughed. He patted his uncle's arm and took the time to correct his fingers. To Mycroft's surprise, he muttered what each sign meant for Sherlock. Mycroft could count on one hand who Artemis spoke to and that was only his immediate family. He stared at Sherlock and wondered how his brother got through to him.

Only hours before Artemis complained about Sherlock being in the room. He was sure Sherlock still hated children but he seem to make an exception for Artemis. The happy look on his little boy's face was real and he had enjoyed himself.

Artemis headed into Sherlock's bedroom to grab his bag and Mycroft focused his gaze on his brother instead. He allowed John to pass as whatever was boiling over finally decided to go off with a loud bang. Slime flew out the kitchen with the explosion and covered the floor in a sticky mess. The doctor cursed Sherlock as he ran to stop the mess from getting any worse. Mycroft inferred that the kitchen was worse than the living room (if that were possible). Sherlock made a noise at John's complaints and sat on his armchair. He noticed Mycroft's gaze and glared back at him.

"Shut up. Not a word."

"I never thought you would willingly spend time with a child, let alone mine."

"Whatever your thinking is not the answer. We had a deal that benefits both of us. It's an experiment."

Mycroft let Sherlock talk, knowing what a terrible lie it was. Sherlock had a genuine smile on his face when he played with Artemis. As if on cue, Artemis emerged from the bedroom and made his way into the kitchen. John's voice went back to normal compared to the shouting he had been doing. He came back out and went to Mycroft, handing him his bag that was held away from his clothes. Mycroft took it and hooked it across his arm. He ignored the snort Sherlock let out and backed out the doorway.

"Say your goodbyes. It is almost your bedtime." Mycroft signed before he texted Anthea to put towels down in the seat of the car.

Artemis nodded and walked back over to Sherlock. He startled the detective by giving him a hug. Sherlock looked down in shock and tentatively returned the hug. The detective's chest got that disgusting warm feeling again as Artemis said a quiet goodbye to him. Pulling apart, thin strands of slime hung between then before dripping down to the floor. He gave Sherlock one last wave as he followed Mycroft out the door.

Sherlock tuned out John's voice as he put his armchair back properly and settled into it. He watched a string of slime dangle from the ceiling when his mobile vibrated.

Expect a call from Lestrade about the mess you have put on Artemis. I believe he will call this another Incident. MH

You made his day, Sherlock. He also told me about your 'deal' and I have to admit, I am pleased that you have taken up a familial relationship with him. Thank you. MH

"You're not even listening to me, are you? Did you just get a text from Mycroft thanking you for watching his kid?" John said from the kitchen, holding up his mobile as he poked his head out.

Sherlock waved a hand in dismissal, staring at the text.

Mycroft watched with a fond look of Artemis signing enthusiastically about his day at Baker Street. He squirmed in his towel covered seat and signed with relish about the afternoon with his uncle. He nodded at the right times as his mobile lit up with a text. He didn't expect Sherlock to answer back, let alone not teasing him about actual being grateful his brother did him a favor.

Text me if you require a babysitter again. My time with my nephew was not unpleasant. SH

His brother was full of surprises. Sherlock had done more than he expected and was trying to save face.

I will keep it in mind. MH

With that last text, Mycroft pocketed his mobile. He felt curious eyes on him and turned to face Artemis. He barely hid a grimace as the towel was turning pink and it would never be usable again.

"I believe that you should blame your Uncle Sherlock for your ruined clothing when get home." he said as Artemis played with his slime coated hair.