Disclaimer: Sherlock Holmes and properties are owned by Sir Arthur Conan Doyle. Sherlock and properties are owned by BBC One, Mark Gatiss and Steven Moffat. Harry Potter and properties are owned by JK Rowling. I don't make money from writing this fanfiction. The story contains spoiler for both Sherlock and Harry Potter. Also there are quotes from the novel and TV series.

Days of the Sunflowers

Harry Watson had found herself a new lover. The said new lover was nice and she made Harry happy. Therefore, John Watson was happy too. Then she whisked Harry away for surprise trip to Bali. Just a few days before Christmas. Thus, led John to his current predicament. Harry didn't have time to buy Christmas present for John so she merely gave him Harrods gift card and told him to buy his own present.

And now, John was standing between clothes shelves at Harrods, confused beyond imagination as what to buy. He wasn't a man of luxury so he didn't need much for himself. He had bought a few things and now planned to buy present for his best friend, the annoying git who faked his own death, the one and only Sherlock Holmes. But, what should he buy for Sherlock? John was busy contemplating this when someone bumped into him.

"Oh, sorry," the person said. The voice was young and childish.

"It's alright," John said. The person who bumped into him was a teen. The teen couldn't be older than fourteen. He was handsome with jet black hair, grey eyes and aristocratic face.

The teen's eyes widened at the sight of him. "You're Uncle John!" he blurted out in surprise.

John blinked. Uncle John? The last time he checked, Harry Watson didn't have a son yet or any child for that matter.

"I'm sorry," he said at last. "But you're mistaken."

"No, I'm not," the boy said vehemently. "You're Uncle John." The grey eyes glinted mischievously now. "You're Uncle Sherlock's boyfriend."

John sighed. "For the last time, we're not a couple," he said in defeat. Honestly, maybe John needed to put note on his forehead or something. Why everyone always assumed that he and Sherlock were dating? Then the teen's words registered on his mind. Wait, what? Did he just hear what he thought he has heard?

"Uncle Sherlock?" he asked incredulously.

"Yes," the teen confirmed.

"As in Sherlock Holmes?" John asked again.

"Yes," the teen replied, looking at John amusedly. "Sherlock Holmes is my uncle. My father is Mycroft Holmes. I'm James by the way. Nice to meet you, Uncle John."

"Nice to meet you, James," John replied automatically. His mind was still reeling from the revelation. Mycroft was a father? How? When?

"Oh! I have to tell them about this!" James crowed happily. "Wait here, Uncle John!"

"What?" John asked, flabbergasted.

But the teen had disappeared.

Sherlock's nephew. Mycroft's son. Never in his life had John thought that Mycroft was a father. He tried to picture Mycroft, Mrs. Mycroft and James together. During all these times, Mycroft never gave any indication that he was a married man. Let alone with a son in tow. James looked quite normal. At least normal like any teen in his age. John had thought that James would start spouting deductions.

"This way!" It was James' voice.

"Are you sure?" An unknown voice joined in.

John remembered that James was going to tell people. What kind of people? He got his answer as James returned, followed by another teen. His twin precisely. They both had the same handsome aristocratic face, messy but stylish jet black hair and grey eyes. The only thing to differentiate them was the colour of their jacket. James wore red jacket while his twin wore blue one.

"See," James said triumphantly. "I'm never wrong." He declared arrogantly.

At that moment, John was reminded of Sherlock.

"Really?" his twin drawled. "I recall many times when you're-"

"It was different," James cut him off before he turned his attention back to John. "This is Ashford, we're twin." He introduced them.

"Nice to meet you, Uncle John." Ashford said politely. "We've heard so much about you." He said.

"All is good, I hope." John said good naturedly.

"Of course." James said.

"We came here to buy Christmas present," Ashford told him.

"Are both of you alone here?" John asked, frowning.

"No," James replied. "We came with Father and Al."

"Al is our younger brother." Ashford explained. "There are three of us."

In ten minutes, Mycroft had gone from single man to a father with three sons in row. How came Sherlock never mention about this before? John never heard about Sherlock's family aside of Mycroft and his mother. And when he spoke about Mycroft, it was usually in annoyance. Sherlock never mentioned about having nephews.

"Have you found present for Uncle Sherlock?" Ashford asked suddenly.

"How do you know about it?" John asked in astonishment.

"Easy," James said.

"You have been here for awhile, looking for things." Ashford said.

"But this section only sells high end man clothes." James continued.

"Clothes that aren't your style," Ashford said again.

"So, you're clearly looking for someone else." James said.

"Someone who is used with luxury," Ashford said.

"The only person who fit the criteria in your circle of friends is Uncle Sherlock." James finished.

During all of this, John merely stared at them in amazement. He should have known that no son of Mycroft Holmes would be normal. They had to be genius too.

"That was amazing," he said sincerely.

"Of course," James said smugly.

"James, Ashford."

"Hey, Al!"

So, this was Al, their younger brother. The teen had the same jet black hair like his brothers but he possessed a pair of brilliant green eyes. And his face... he must be the most adorable child ever.

"Look!" James pointed at him excitedly.

John thought that he was paraded around like animal in the circus.

The green eyes widened in recognition. "Hello, Uncle John," Al greeted him. "I'm Albus but just call me Al." His voice was soft. It was contrast with James' boisterous one.

"Hello, Al." John said, wondering as to why Sherlock's nephews knew about him while he didn't know that they existed until ten minutes ago.

"Hello, John. Good to see you," And from behind Al, Mycroft Holmes showed up. As usual, he was dressed impeccably in his three piece suits and black coat.

"Mycroft," he said.

"Father, we found Uncle John here," James told his father in excitement.

"Yes," he drawled. "John," he said."Let me introduce my sons. James and Ashford are the oldest. They're twin."

James and Ashford wore matching grin on their face.

"And Albus, my youngest son." The man put his hand on Al's shoulder as he introduced them.

Al smiled at him.

The sight of Mycroft surrounded by his children was really something. Sherlock said that he was married to his job and John assumed the same for Mycroft. This was Mycroft he was talking about. The British Government.

"So, John, have you found suitable present for my brother?" Mycroft asked.

"How? Never mind about that." John muttered.

"Scarf will be nice," Al suggested.

"Yeah," James said in agreement. "Uncle Sherlock always wear scarf."

"True," Ashford added.

Facing with three hopeful expressions, John knew what to do, even without Mycroft's threatening gaze in the background. Mycroft was such an over protective brother. John shuddered to think about the level of protectiveness Mycroft achieved as a father.

"That is excellent idea," he said.

James cheered.

"Over there," Ashford pointed.

They finally settled on nice blue cashmere scarf. So, John went to pay for his purchase.

"We have to leave now." Mycroft said. "See you, John."

Apparently they were finished with their shopping.

"See you, Uncle John," the children chorused.

XXXXXXXXXXXXXXXXXXXXXXXX

John was still confused when he returned to 221B Baker Street. Sherlock took one look at him and said. "You've met them."

"Yes," John huffed. Really, there was no secret there. "Why you never tell me that you have nephews?" he asked curiously.

"It isn't important," Sherlock answered.

John sighed. "I didn't even know that Mycroft is married."

"His ring, John," Sherlock said annoyance, probably amazed by John lack of observation.

"I thought that the ring is symbolic," he said sheepishly. "You're married to your job. He's married to his job. Symbolic, like I said."

Sherlock snorted. "You really do have imaginative mind."

"You like your nephews, right?" Somehow he had to ask Sherlock about this. Sherlock called Mycroft his archenemy after all.

"Don't be stupid, John." Sherlock drawled. "I'm quite fond of my nephews."

"That's good to know." He muttered. "They never visit you here." He commented.

"Most of time they're in boarding school." Sherlock replied.

"Eton?" he asked, "or Harrow?"

"It's private boarding school in Scotland." Sherlock said. "There is no escaping them now."

"What?" he asked, confused by his best friend statement.

"Do pay attention, John," Sherlock said, annoyed. "You've met them, finally. Now, they're going to kidnap you for Christmas dinner."

"They're teens," he retorted. "I doubt they have ability to kidnap someone." He said dryly. The only thing they could do was asking their father to do the kidnapping. Mycroft was a professional in that area.

"They're his children," Sherlock said, as if that explained everything. "Those three pranksters."

"Maybe James," John commented.

Sherlock snorted. "Oh, they're equally mischievous."

"Hmmm..." he muttered. "I'm going to make tea. Do you want some?"

"Yes." Sherlock replied.

Mycroft came the next day when he and Sherlock were having breakfast. "Good morning, little brother, John," the man greeted them.

"Morning, Mycroft," John replied.

Sherlock didn't bother with replying his brother.

Mycroft, used to it, simply said. "I came to invite both of you to Christmas dinner this year."

"Fine, I'll come." Sherlock said curtly.

John looked at his best friend in shock. If anything, he thought that Sherlock would refuse. Especially with his comment about the Christmas dinner previously.

"And what about you, John?" Mycroft asked.

"I'll come too," he replied.

"Good. That's very good," Mycroft said smoothly. "Well, now that's settled, I will take my leave then. See you later, Sherlock, John."

As soon as Mycroft left, he turned to Sherlock. "We need to buy present for your nephews."

"I suppose," Sherlock said. "We could go to Harrods then. You did go there to buy my Christmas present. Scarf, really, John."

John groaned.

"Christmas dinner at Mycroft's house?" Mrs. Hudson said in surprise.

"Yes, Mrs. Hudson," John replied. Their landlady had come to inquire if they were going to have gathering at 221B just like last year. "I met him and his sons a few days ago." He added.

"Sons?"

"Mycroft has three teenage sons." John explained.

"He must have his hand full," Mrs. Hudson commented. "Did you meet his wife too?" she asked eagerly. This was really a new piece of gossip.

"No," John replied."Only him and his sons."

She looked disappointed.

"But we could have gathering at New Year," John suggested. "Three of us plus Molly and Greg."

"That' splendid idea," Mrs. Hudson said. "We should invite Mycroft and his wife too."

John very much doubted that Mycroft would come but Mrs. Hudson was quite adamant so he gave up and said that he would ask Mycroft.

XXXXXXXXXXXXXXXXXXXXXXXXX

Mycroft send his chauffeur to pick them which was great since it was really difficult to find cab at Christmas Eve.

"I thought he lives in Pall Mall," John commented when he arrived at the magnificent manor that was Mycroft's house in Campden Hill, Kensington.

"It is his official residence," Sherlock replied.

The massive front door opened and Mycroft showed up. "Good evening, Sherlock, John, I'm pleased that both of you make it," he said.

"You did invite us here," Sherlock commented, walking past his brother.

"Evening Mycroft," John said.

Mycroft closed the door and gestured to the long hallway. The house was huge. The classic English decor was enhanced by fine details such as Victorian antiques, priceless paintings and elegant fireplaces. Christmas decorations artfully completed the places.

"Sherlock!"

John looked up and saw a man, probably in the beginning of thirty, greeted Sherlock enthusiastically. The man turned to him the next. "Dr. John Watson, we finally met, at last."

John really needed to talk with Sherlock about the fact that everyone seemed to know about him.

"I'm Harry, Harry Potter." The man said. "Just call me Harry."

Harry again? So many Harrys in John's life. What was Harry's connection with Sherlock then? An unknown brother, perhaps?

"Uncle Sherlock!" The children had spotted their uncle presence.

Harry smiled brightly at them. "Sherlock is quite close with the children," he commented.

"Yes, he encourages their mischievous streak," Mycroft said.

"I could say the same about you, Mycroft." Harry said.

"Forgive me, dear."

Dear? John stared at both of Harry and Mycroft. It was then that he noticed that Harry's green eyes were identical to Al's.

"Mycroft is my husband," Harry said. "James, Ashford and Al are our children."

"Oh, that is-that's fine." John said lamely once he found back his voice. Not a wife but a husband. He was going to kill Sherlock and Mycroft for making a fool out of him. John fumed inwardly as he walked towards the dining room with Mycroft and Harry. Sherlock was behind them. He was busy conversing with his nephews.

The food was absolutely delicious. But then again, that was expected from Mycroft. After dinner, they retreated to the living room. Mycroft and Harry sat side by side on the sofa. Sherlock sat on the armchair with bored expression on his face. John sat opposite Sherlock. The children sat on the other sofa.

"So, John," Harry began. "I read your blog."It is really informative.

"Yeah," James piped up. "We read your blog too."

"It's really interesting," Ashford added.

"Thank you," John said, pleased. He gave Sherlock a pointed look.

Sherlock ignored him with practiced ease.

"Both of you are so funny," Harry said after watching their interaction.

"I'm not funny!" Sherlock argued vehemently.

Harry ignored his protest.

James snickered.

Sherlock gave his nephew a betrayed look.

"It is good for Sherlock to have John with him," Mycroft stated.

"I'm sitting right here," Sherlock said sarcastically.

"So, what do you do?" John asked Harry, intent to prevent the war between the two brothers. Really, it was Christmas Eve and they still managed to bicker like a child.

Harry and Mycroft exchanged look before he said. "I'm Chief of United Kingdom Special Defence Force."

"Is that part in our military?" John asked.

"More like law enforcement," Harry said. The man was nice and friendly. He was also normal. It was stark contrast with Mycroft. John was quite content to talk with Harry while Mycroft inserted his opinion here and there.

It was when he heard the word blackmail; he turned his attention to Sherlock. Just what Sherlock was doing with his nephews?

"We're telling Uncle Sherlock about the computer program that we've created," James explained upon seeing John's expression. "We named it Marauder." He said proudly.

"Virus," Sherlock corrected.

"Spyware," Al said.

"Do tell about that," Sherlock ordered his nephew.

"Marauder is meant to gather information from infected computers. It can sniff out information from input boxes, including password hidden by asterisk, record audio from a connected microphones and take screenshots of applicants that the spyware deems important." Al explained. "It can also collect information about nearby discoverable Bluetooth devices. It won't disturb or destroy anything. After initial infection, the spyware can spread through USB sticks or local network."

By the end of Al's explanation, John was rendered speechless.

"Clever, very clever." Sherlock commented. "How do you hide it?"

"It appears to infect computers disguised as legitimate program." Al explained.

"It might come handy in the future," James said. "For blackmails," he added, grinning widely.

"Interesting," Sherlock said. "We'll discuss about this later."

"Of course, Uncle Sherlock." James replied.

"We have tested it." Al continued. "The result is perfect. We've gathered many information. Father has seen it."

Mycroft inclined his head towards his youngest son.

"Dirty laundry actually," James said wickedly. "You won't believe what those politicians at Whitehall did in their spare time."

"I'm going to test it in Scotland Yard," Sherlock declared.

"Okay, Uncle Sherlock," the children agreed readily.

John was horrified.

Harry looked exasperated at his children antics. "You children have too much free time during holiday," he muttered. "Whose idea is this?" he asked.

"It's me, Dad." Al answered.

John's mouth literally fell open. He stared at Al in disbelief.

Sherlock gave him 'I told you so' look.

"I think it will be useful," Al admitted.

"Hmmm...planning to be the future British Government?" Sherlock asked.

"Sherlock!" John hissed in warning. But he didn't need to worry.

"Well, England is just one country. Even if we add the Commonwealth, it's only a small portion of this world." James said. "No offense, Father."

"None taken, James." Mycroft replied. He had a slight smile on his face.

"If we're going to do it, we won't do it by halves," Ashford said.

"What do you mean by that?" John asked. He couldn't help himself.

"We're going to rule the world." Al said.

Mycroft looked every inch of a proud father. He couldn't be more delighted to hear that his children wanted to follow his step.

Harry merely sighed.

Sherlock had thoughtful look on his face. John was afraid to ask what he was planning with his nephews.

And for the first time, John saw the steel determination in those green eyes that Al possessed. Not only Al, but also James and Ashford. Brilliant sharp mind added with the resource their father had. The world better be ready for the Holmes siblings.

Author's Note:

This is my sixth Sherlock Harry Potter crossover fic. I just move to another investment bank so now I'm quite busy and can't update as fast as before. I want to write about Harry and Mycroft's teenage children but it's impossible to do so in Winter Tale. So, I decide to write this. I think it is really interesting to explore that. Arthur Bowen, who starred as Al in Deathly Hallows the movie looked really cute and adorable there. If any of you have idea as to the next that could happen, please tell me. Thanks.