Mycroft and Anthea let themselves into 221B Baker Street on a cold winter's day in late November without bothering with such humdrum minutiae as knocking or checking if anyone was home. Sherlock and John were both there of course; they wouldn't have bothered entering, otherwise.
"No," Sherlock said pointedly, not bothering to rise from his comfortable armchair or even look up from the latest mycology journal issue he was poring over.
"What's that?" John called from the kitchen.
"My brother's here, and whatever he wants, the answer is 'no'. I'm busy."
"Cup of tea?" John called out.
"Thank you. English breakfast, black, no sugar," Mycroft replied. "Nothing for Anthea."
Sherlock sighed in a put-upon manner and resolutely concentrated on his journal, determined to cause as much inconvenience to his brother as possible.
John emerged from the kitchen and handed a cup of tea to Mycroft then put another one on a messy side table near Sherlock. Anthea looked at him briefly before returning her gaze to a baby car seat carrier she'd set down at her feet, next to the briefcase she'd also brought in. A serious-faced infant, a young boy of perhaps six months old, was returning her intent watchful gaze with a stare of his own. His hair was a dark fluffy fuzz on his head, and he was dressed in a little white jumpsuit with a hood.
"Good grief," John said, walking over and squatting down near the baby. "Hello there, little man!"
He frowned as he looked closer. "Why are the straps secured with zip ties?"
Mycroft smiled thinly. "He enjoys testing the manufacturer's claims of 'child-proof', and we didn't wish to have any incidents so close to handover."
"Handover?"
Sherlock put his journal down with an angry huff. "No!"
"Yes. You will look after the baby," Mycroft said. "There is no-one more suitable, and I have been entrusted with his safe disposal. This is the best approximation of a loving home that will cope with his challenging nature."
Sherlock glanced over at the baby in the car seat, eyes flicking over it in an assessing manner before finding it clearly uninteresting and picking his journal up again and pretending to be engrossed once more. "Ridiculous. Out of the question. I don't want a baby."
John sighed and rubbed his forehead tiredly. "Where... where did you get a baby? Who would give you a baby to 'dispose' of, and what on earth makes you think Sherlock is suited to caring for one? It's obviously not his. It isn't, right?"
"Of course it isn't!" Sherlock pronounced definitively. "No familial link to any of us."
"We seized it from Abstergo," Mycroft explained.
"Who? Why?" John asked.
"Abstergo Industries is a multinational pharmaceutical and health insurance industry with its head office in the US and branch offices around the world including, most relevantly, in London. It produces overpriced but high-quality drugs, with subsidiary companies involved in medical technology and video game development," Sherlock rattled off quickly. "They have released a number of VR games with the most successful focusing on immersive historical scenes. Their depiction of Notre Dame is… adequate."
"Sherlock that's… look," John said, before starting again. "That certainly is interesting, but it doesn't answer why Mycroft has been entrusted with a baby from who… the company CEO? Is the baby a kidnap risk?"
Sherlock, in a bored tone of voice, answered on his brother's behalf, since Mycroft was only smiling thinly. "State secret. Obviously. Babies are dull. Give it to John. He'll see it gets to some kind of foster care if you can't be bothered with the details."
"You might find this one a tad less dull, Sherlock, it's a fellow high-functioning sociopath."
John raised a tired hand to his forehead. "Babies aren't sociopaths."
"All babies are sociopaths."
"Sherlock!" John objected.
"It's true. You're a doctor, John, you should know this. They all break laws, act impulsively, and have no regard for their own safety or the safety of others. They have an utter lack of interest in the concerns of others, or society's dictates, and no conscience. Sociopaths. Dull. They grow out of it."
Mycroft gave his brother a wordless smirk.
Knowing his brother's expressions, Sherlock took that as a challenge, and frowned. Had he missed something? Of course he had. He needed more facts. "What's different about this one?"
Mycroft sipped his tea primly, setting down his cup with a clink. "He killed three of his nannies at Abstergo. One with a knife, the next with broken glass from a baby food jar. After that they learnt to keep anything remotely dangerous well away from him. The third he killed with a sharpened plastic spoon and a lot of ingenuity, then tried to escape their London headquarters. He didn't make it out of the building, but he managed to draw attention from the authorities. That is where I came in, in rather short order."
John looked flabbergasted. "He's joking. Tell me he's joking. He's not more than six months old!"
Sherlock steepled his fingers. "He's not. Fascinating…" He reached out for the baby, getting out a pocketknife to cut the zip ties.
The baby's face scrunched up in anger, and he shrank back in his carrier. "No!" the baby cried out with impressive comprehensibility for his age, then let out an ear-piercing scream that had Sherlock wincing and drawing away.
"I would listen to him if I was you, and be very careful with that knife," Mycroft said, watching with faint amusement as he returned to his tea. "He is rather particular about who he trusts to handle him and possesses an unusual level of discernment. He alerted us to an attempted kidnapping by an undercover Abstergo employee with an exceptionally piercing scream."
The baby looked around and focused on John, eyes narrowing intently. He reached out with chubby hands making grabbing motions. "Boo. Ub! Ub!"
"He wants you to pick him up, John. My, you are favoured. He doesn't call many people blue. I was gold, then demoted to grey for some reason we are yet to completely discern, not having a large enough sample. My working theory is that gold people help him accomplish his goals. He has an intriguing colour-based system for rating those he meets."
"Did the knife scare him? Just how abused was he?" John asked in bewilderment. "Did he really kill people? Why?" He reached out to gently pat the baby on his head.
"He acted in self-defence, of a sort. I assure you they did not have his best interests at heart."
"A pharmaceutical company with undercover operatives who get past your background checks, Mycroft. How interesting," Sherlock mused.
Sherlock turned to the baby.
"I wasn't going to hurt you," Sherlock explained. "The knife was for the zip ties. Not to hurt you."
"No," the baby burbled crossly, looking from Sherlock to Mycroft. "Wed. Wed."
"Red. Oh dear," Mycroft said. "What did you intend to do with him once you had him out of the carrier?"
"Just a few basic experiments to determine the range of his abilities. He has atypical motor control and speech for his age."
"He does not enjoy being experimented on, Sherlock. You will remind him of his nannies."
"Some kind of hideous child experimentation project?" John asked. "The nannies all hurt him?" John looked him overly more carefully. As he pushed up the infant's sleeves he found needle marks and scars on his chubby little arms, and let out a sharp hiss of anger. "You poor little chap."
Mycroft nodded. "Yes. Evidence suggests he is an illegally produced clone. According to the records and samples we found, there were three babies before him, all… disposed of. Their project has been shut down… for now… but we are only just scratching the surface of the depth of the company's hidden operations. A secure home off-the-books is required while we sort this mess out. He is not flourishing in the stark facility we have been keeping him in so far and has made our nannies understandably nervous. We expect more retrieval attempts so an ordinary foster home is obviously unsuitable. There may be some danger in keeping him."
"We don't mind that, do we?" John cooed. Under Anthea's directions he emptied out his pockets… a gun, a knife, a couple of pens, then she snipped the zip ties and backed off quickly, letting John unclick the straps and get the baby out for a cuddle.
"You going to be a good boy for me? I won't hurt you, little man. We will keep you safe."
"Boo," the baby said happily, resting his head on John's shoulder with a pleased sigh.
Mycroft turned to address the baby, with a serious expression. "Just so you know, Seventeen Delta, I will not hold it against you if you stab my brother if he's exceptionally annoying and tries to experiment on you, so long as it's not a fatal wound and you both make peace with each other afterwards. Do be gentle with John, though. He'd take such a thing to heart. You'd be much better served getting my brother on your side, as you won't find more fierce protectors anywhere than these two. They'll kill to protect you. John will keep Sherlock in line in regard to his temptation to experiment, and between the two of them they'll teach you everything you want to know."
"No experimenting on the baby, Sherlock," John said sternly. "You know my rule."
"'No human experimentation without informed consent, no animal experimentation without the owner's consent'," Sherlock quoted, with a pained air. "But how am I to learn anything? He's not old enough to properly consent and parental consent is inapplicable here."
"He's smart, aren't you?" John said, half to Sherlock and half to the baby snuggling in his arms. "You can ask him."
"A genius serial killer baby," Sherlock mused.
"Merry Christmas," Mycroft said, with a smile.
"It's November."
"Don't be tiresome, it's an early Christmas present. You always wanted a pet serial killer of your own to study. Someone unique, mysterious, intelligent, and not too personally dangerous. Seventeen fits the bill even more than John does."
"I'm not a serial killer! I was in the army, that hardly counts," John objected, but Mycroft just smiled in reply.
"True," Sherlock said, looking with increasing interest at the baby in John's arms. "Very thoughtful of you, I must admit. I would thank you, but as this is also a favour to you, perhaps we're even."
"Does he have a name? Surely Seventeen Delta isn't his name. Did he only get a lab number?" John asked. He bobbed up and down gently as he cradled the child against his shoulder. "Any tips on avoiding getting stabbed?"
"His designation is Seventeen Delta, and he responds well to Seventeen. If he was given another name it was not in his records, and he has objected to being given another name; we tried a few and all were loudly rejected.
"Being kind and protective seems to be sufficient to avoid attacks. No experimenting on him, no needles except from blue-rated people who have given advance warning. Unfortunately, I am reluctant to leave him with you both unless Sherlock manages to shift his rating from red to a less worrisome colour. Seventeen does not seem inclined to hurt those that do not threaten him or work for Abstergo, which is encouraging, but a red rating still poses an unpalatable risk."
"How tiresome, I thought you said he was a gift," Sherlock complained.
"Still, I would rather not see you stabbed in your sleep. Consider winning him over as a challenge; part of the gift," Mycroft suggested, with a challenging look.
"You could try cuddling him without holding a knife," suggested John.
"I want a gold rating," Sherlock replied. "What does a tiny serial killer lab experiment want?"
"I think–"
"Shush, John, I'm thinking."
Sherlock huffed with frustration, then steepled his fingers as he leant back in his chair, lost in thought. After a moment he stood and walked around to where Seventeen could see him, peering at him suspiciously while he clung tightly to John with tiny fists.
"I give you my word I shall not experiment on you without your full informed consent, and that I shall investigate Abstergo Industries. I will find out who was responsible for experimenting on you, and how and why, and to the best of my ability I will see them imprisoned, or, if American and resident in the right states, executed for their crimes. I have ensured capital punishment for my landlady's former husband, if you would like a reference. I cannot guarantee a conviction, as that relies on intelligent and cooperative police and those are sometimes in short supply, but I shall play my part to the fullest. Additionally, I shall ensure you have a weapon on you at all times, so long as you do not use it on John or I, and I shall see to the more interesting parts of your education. Shooting, poisons, tracking, and so forth."
"God, Sherlock," John said, with a sigh. "Can't you just promise to look after him?"
The baby gave Sherlock a slow, slightly wobbly nod. "Es. Gowd."
He reached out with a tiny hand, which Sherlock took and shook gravely like they were concluding a business deal.
"I think the results speak for themselves, John," Sherlock said triumphantly, rubbing his hands together with glee. "If he only wanted coddling, he would have been happy staying with Mycroft. Gold! Excellent. This should be interesting."
Anthea snapped open the locks on a briefcase and pushed aside a pile of papers and half-completed scientific projects on the table to make room for the paperwork she extracted from the suitcase.
"Watch out, that cheese is an experiment," Sherlock objected, as she started moving some mould-filled beakers around.
"We're going to have to clean up a lot in here," John mused, looking around. "That mouldy cheese is just the start."
Anthea laid out some paperwork on the table and put a pen down next to it. "Case file?" Sherlock asked eagerly. "No. Red tape. How dull."
"Adoption paperwork and associated other bureaucratic forms. Or foster care, if you prefer a less permanent arrangement. Sign them and you get the baby and the case file."
"I'm not passing him on to someone else if I have to spend effort raising him. He is only going to get more interesting once he can walk and talk properly."
"He's quite the speedy crawler for his age," Mycroft observed, as Sherlock skimmed through the paperwork and began signing things. "Good at climbing too, and he can 'cruise' walking around if he's holding onto something. No independent walking yet but he is working hard at it. Seventeen's estimated age is six to seven months, so an appropriate birth date has been selected."
"Sign here, John."
"Seriously?"
Mycroft tutted. "You surely can't be considering Sherlock as having sole legal responsibility for a baby, John? He needs two parents. Mummy insisted."
"That explains the other paperwork," Sherlock mused aloud.
"I suppose you have a point," John conceded. "Oh, alright, take Seventeen, and let me read through all this."
"Just sign it, John," Sherlock huffed impatiently. "Can I have the case file yet?"
Anthea glanced over at Mycroft who shook his head. "Only once the paperwork is complete," she said.
John shuffled through the papers as Seventeen wiggled around in Sherlock's arms, reaching inside his jacket and grabbing a metal fountain pen from a pocket with a triumphant, "Ha!"
Sherlock hummed thoughtfully and reached into his trouser pocket. "Wouldn't you rather have a penknife?"
"Sherlock!"
"I did promise, John. Best to treat him as a miniature adult with PTSD, I believe. He has the intelligence and reactions of one."
Seventeen shook his head. "No nife. Hawd oo oben."
"Consonants giving you difficulty? The knife is too hard to open, is that right?" Sherlock checked.
"Es."
"Some kind of easily triggered flick knife then, I shall go shopping."
Seventeen burbled happily, and hid the pen in his nappy for now.
"My, he is chatty with you now. He usually sticks to single, simple words to better disguise his intelligence," Mycroft observed.
"Dull. Also, it is probably hampering his speech acquisition if he is leery of practicing. I expect better efforts to talk now you're with us, Seventeen, so long as we're not in public. Is that acceptable?"
The baby gave a serious, albeit slightly wobbly, nod of his head.
John sighed. "Only you, Sherlock, would prioritise an illegal knife for a baby over a cot and bottles. Right, I'd better sign this then. If it doesn't work out you will find another family, of course?"
"Certainly," Mycroft agreed. "If that is acceptable to you both."
"Marriage paperwork?!" John cried out, aghast, as he continued looking through the forms. "Sherlock, did you even look at what you were signing?"
"Of course I did," Sherlock said, "I don't read as slowly as you do. There's a sticky note; did you not see it? Mummy insists that she doesn't want her grandchild growing up in a single-parent household. Do sign it so I can get the case file, John."
"That is the worst proposal I have ever heard in my life. I thought you were asexual."
"Asexual demiromantic, yes," Sherlock said, assiduously avoiding eye contact with John as he jiggled the baby in his arms. "I would not be averse to forming a platonic life partnership, should you be interested. I would hope for romantic but not sexual fidelity."
"Fuck. Fine. I suppose we may as well make it official," John said, and scribbled his name down.
Mycroft smiled again, and signed the paperwork too, as did Anthea after him, putting down their names as witnesses.
"Not the wedding I always dreamed of. Nor is my partner," John said, looking over at Sherlock who had wandered into the kitchen and was gravely and curiously inviting Seventeen to demonstrate how hard he could jab various objects with the pen he'd purloined. A slice of bread was easily stabbed, while an apple proved to be more challenging but still within the baby's capability. He might not have a lot of strength, but what he had he used to its utmost.
"Cheer up, brother," Mycroft invited, giving John a little smile. "It does come with a family bank account to cover expenses, so the arrangement is not wholly without its perks. Welcome to the family. I hereby pronounce you life partners; I suppose you may hug the groom."
John laughed, a little unbalanced, but walked up behind Sherlock and hugged him from behind.
Sherlock let out a mildly surprised squawk but relaxed back against John. "This is nice, I suppose. Am I to expect an increase in tactile affection from now on? I would not be averse to receiving back and foot massages, if so."
"Only if they're reciprocal. My shoulder could do with a bit of a massage from time to time."
Sherlock set Seventeen down on the kitchen counter and turned to face John with a smile.
"Don't leave him there!" John cried, pushing past Sherlock to scoop up the baby. "He'll fall, or pull the kettle onto himself."
"That sounds unlikely. He seems highly intelligent and has good motor control for his age."
"Accidents still happen."
"No," Seventeen said, looking cross.
"We're your new daddies now, Seventeen. Is that alright with you?" John asked, cradling him in one arm.
The baby tilted his head thoughtfully, then nodded. "Es. Dada."
A wide smile blossomed on John's face as he gazed at the baby in his arms and Sherlock tentatively rested a companionable hand on his shoulder. A soft clicking noise from the background suggested either Mycroft or Anthea had snapped a picture of them.
"Mummy will like that," Mycroft said with satisfaction. "She did want a wedding photo."
"An instant grandchild," Sherlock said, squeezing John's shoulder and looking down at Seventeen with pride. "Much more conveniently acquired than the rather distasteful conventional procedure."
"What do you say?" Mycroft prompted.
Sherlock blinked at him. "If I must! Case file please."
Mycroft sighed. "I was hoping for a thank you, but that's close enough, I suppose."
Sherlock took the case file and started reading through it, while John kept Seventeen entertained (or possibly annoyed) by being bounced and fussed over while John babbled about all the things they'd buy for him and pondered out loud about how they could rearrange the flat.
Anthea and Mycroft were almost out the door when Mycroft heard Sherlock say softly, "Thank you. An early 'Merry Christmas' to you too, brother."
-000-
This story was inspired by esama's collection of ficlets titled "Badass With a Baby".