Note: I own nothing but my own plot, everything else is the BBC's, Stephen Moffat/Mark Gatiss's, and Arthur Conan Doyle's. I just like to play here. Not beta'd or Brit-picked.

This is the fourth story in the "Heritage" series—where I take one fact and change it, watching in wonder as it alters every aspect of the story. In all of them, John is the grandson of an earl but the rest of the army-doctor thing and being invalided out to meet Sherlock Holmes all stays the same. In the first one (Heritage Trust), though, we found out that his father was abusive when he was a child, which is why he felt he had to leave home and keep his past a secret. The second story (Trust Heritage) was a mirror image and made his father a good father, but John still had reasons for striking out on his own. The third made John's father the earl's eldest son rather than the younger—which made a dramatic impact on John's inheritance. And now, well … you'll see! Each story, though, covers more or less the same time period, and while it might help to read them in the sequence I wrote them if only to see what changes I've been making, it's not at all necessary. Have fun! (I know I am.)

#

John was sitting staring at his laptop when his phone rang. He looked at the caller ID and groaned, leaving it untouched on thetable.

"Problem?" Sherlock's voice came from across the kitchen, where he was measuring something malodorous into a test tube.

"No, it's just Harry," said John. "Probably wanting to confirm Sunday."

"That seems odd," Sherlock said, voice somewhat absent as he concentrated. "You visit her every Sunday. Why would she need to confirm?"

John stared even harder at his computer screen. "Exactly. She probably just wants to gripe about Clara some more, and really, she's going to see me in two days. Surely it can wait until then?"

"In my experience, women are notoriously needy when it comes to talking about their feelings," said Sherlock. "I thought they had split up? You're not going to need to get a new phone, are you?"

John blinked for a moment, confused, and then remembered the inscription. "No, that phone is mine now, but they've been trying to work things out. It just hasn't been going so well."

He saw Sherlock nod, eyes fixed now on his microscope as he said absently, "For the sake of the kids, no doubt."

Really, John thought, as his phone began to ring again, he had no idea.

#

It was only an hour later when everything changed. He and Sherlock had been called to a crime scene and were in the middle of examining a 20-year old woman's mutilated body when his phone rang again. Glancing at the ID, he answered it this time, "Clara?"

"John, I need to see you."

"I'm sorry, what?"

"You have to … look, she's drunk again, and I can't … It's not safe and … I just can't deal with this right now."

John had edged away from the body now, as if shielding the distraught woman on the phone from the gory scene. "I'm kind of … no, right. Of course. Where are you?"

"I'm right outside, John," she said, hanging on to her wits by the merest thread.

"Outside the flat? Okay," he told her. "Look, go into Speedy's and get some tea and a snack. I'll be there in about fifteen minutes-half an hour, tops. Just…"

"No, John. The crime scene," she said, just as a constable came bustling in.

"Dr Watson? You've got … there's a woman outside …"

John shoved the phone back into his pocket and turned to find everyone staring at him. "Tell her I'll be right there," he said, forcing himself to focus on one problem at a time. "As near as I can tell, it looks like this woman was dead before the killer started using his knife—there's just not enough blood otherwise. Asphyxiation seems the best bet, judging by the skin. I'd check to see if there are any fibers in her mouth or lungs. Dead 10–12 hours, I'd say, and now I've got to go." He stripped off his gloves while he was talking and was already heading for the door as he finished.

"John? Where are you going?" Sherlock sounded almost bewildered.

"Everything okay, John?"

At least Lestrade sounded concerned, thought John as he gave a nod. "Family emergency. Sorry. I'll see you back at the flat later, Sherlock."

He edged out the door and hurried through the flat and out to the street, trying to ignore the trail of curious people following him. Seriously, there was a woman lying dead inside and they were being nosy about his personal life? But all that dropped away when he saw Clara, standing by the tape line looking like she was about to burst into tears, as if the only thing preventing it was sheer force of will.

That, and the hand of the equally-distraught nine year-old boy standing right next to her.

"Clara," John said in greeting as his eyes went straight to the tear-streaks on the boy's face. "Ian, you doing okay?"

The boy nodded and then switched to a head-shake as his face crumpled and he ducked under the tape to fling himself into John's arms as Clara said, "I'm sorry, John, but I just can't deal with her right now, and I can't leave him alone, and it's Hannah's day off. Can you take him?"

"I…" John was kneeling now, soothing the boy as best he could. He thought about the state of their flat, thought about Sherlock and his tendency to run out the door, expecting John to be right behind him. He thought about how ill-fit his lifestyle was to look after a child, how little experience he had. But … what was he supposed to do?

Without even thinking about it, his arms curled protectively around the boy's shoulders, unwilling to let him go. And, really, he owed her. He nodded. "Of course. How did you find me?"

She gave a small, frozen smile. "You have her phone."

Right, of course, thought John. And he had never thought to disable the tracking, so of course she would be able to track her spouse's phone. Ex-spouse. Whatever. " How long…?"

She thrust a rucksack at him. "There are a couple changes there, hopefully they'll be enough until Harry's capable again. Be good for John, okay, sweet boy? I'll see you soon?" Leaning forward, Clara gave Ian a kiss and then placed a quick peck on John's cheek as well, her eyes moist. "Thanks, John. Sorry."

Before he could say anything, she was gone. John rose to his feet, boy still in his arms and turned to see Sherlock, Lestrade, and Donovan all standing, staring. "Ex-girlfriend, John?" Sally asked, a sneer in her voice.

"Ex-, current-, soon-to-be-ex-again sister-in-law, actually," he said, keeping his voice as even and calm as he could.

"So, this is your nephew then?" asked Lestrade in a friendly voice as he smiled at the tearful child in John's arms.

"Something like that," said John. "Look … I need to… I'll see you all later. Come on, Ian."

And picking up the rucksack, he walked away.

#

Sherlock didn't know what to expect when he arrived home later. He was still reeling from the surprise that John had a nephew. Or, not so much that he had one, but that Sherlock had missed all the signs.

Because of course John Watson would be a responsible uncle, one who his sister could rely on in an emergency. Dropping him off at a crime scene was unexpected, of course, but clearly this had been a crisis. John's sister had apparently gotten drunk and alienated her wife to such a degree Clara didn't even want to stay in the house. Naturally, she couldn't leave the boy alone with an inebriated mother … though he was uncertain why she felt she needed to leave the child with John rather than bringing him with her…

Still, family emergencies happened, he supposed. He just hoped it wouldn't be a common occurrence. The thought of having a child at 221B at all was annoying, but if this were going to be a regular habit … He supposed he needed to be patient. He already knew John and Harry didn't get along. John wouldn't want responsibility for her child any more than necessary.

Or at least he hoped not. Sherlock didn't have anything against children … particularly. Unless they were running in circles or making a mess, they weren't any more annoying than adult people—if anything, their open minds and untrained, but willing way of observing the world made them less annoying. Being children, they weren't expected to know things (yet) … so it wasn't actually their fault when they didn't. In fact, they usually appreciated your teaching them things—unless you opted to use the wrong word or discussed dissecting kittens or something else that made them inexplicably start to cry, because crying very definitely was annoying.

No, as long as they behaved themselves, children weren't impossibly annoying.

But that didn't mean he wanted one in his flat.

He considered the way John had avoided Harry's phone call earlier. He thought about the desperate look on Clara's face when she dropped off the child—the way her hand had curved around his head, the way her shoulders had straightened as she walked away. She had looked for all the world like a woman saying a permanent goodbye.

That was curious, though. Even if she and Harry were getting divorced, wouldn't Clara be the likely one to get custody, not being an alcoholic herself? (Not only had John never mentioned such a thing, but her skin tone and the colour of her fingernails argued for her being clean.)

He thought again about the little boy, the shade of his hair, the tilt of his nose. He looked like a Watson, and he assumed that Harry had been the biological mother but … flashing back to Clara's distraught departure, the way John had wrapped his arms around the child … what if John had been the father? But, still, wouldn't that logically mean that Clara would have been the biological mother, and therefore have more legal rights than her farewell just now had implied?

John would probably tell him it was wrong to be so delighted at the prospect of a mystery that held a bereft little boy at the heart of it.

#

With unusual thoughtfulness, Sherlock refrained from bounding into the flat with his usual energy, just in case John's nephew (?) was still there and sleeping. It would be prudent not to frighten the child, which would only put John in a bad mood.

He found the boy awake and sitting on the couch, wrapped in a blanket and sipping at a mug as he watched telly. John was sitting next to him, book in his lap. "Hello, Sherlock," he said. "You're later than I expected. You weren't avoiding us, I hope?"

There was a twinkle in his eye, so Sherlock deduced that John was teasing him. "Don't be ridiculous, I was helping Lestrade with the case. You were right, the woman was killed with a…"

John cleared his throat loudly, cutting him off with a sharp look at the child. Of course. He supposed the gorier bits of information about a murder weren't exactly appropriate conversation in front of a … nine year-old?

"Of course," was all he said, trying not to stare at the boy, but unable to stop cataloguing the shape of his fingers and curve of his ear. The way the two of them were tilting their heads at just the same … oh.

"Questions?"

Sherlock looked at his friend, noting the white at the lips, the lines of strain in the forehead, as his fingers curled around the boy's shoulder. Then, before he could help himself, he asked, "He's not your nephew, is he?"

John's smile grew wistful as he said, "Ian, this is my flatmate, Sherlock Holmes. Sherlock, this is Ian … my son."

#

"You have a son?" Sherlock was unused to hearing his own voice sounding so surprised.

John just nodded, face wary. "I do, don't I, Ian?"

The child nodded his blond head. "But I live with my aunts because Dad was in the army."

"I … see," said Sherlock, and he did. Of course John wouldn't have been able to look after a child while he was deployed. But what had happened to…?

John had a smile on his face, as if he knew exactly what was going through Sherlock's head (and wasn't that a change of pace!). He leaned toward his son and whispered loudly, "He's wondering what happened to your Mum. Do you think we should tell him? Or let him figure it out?"

The boy … Ian … giggled a bit. "Can he?"

"Oh yes. Sherlock can figure out almost everything." He looked over at Sherlock face alight with something that almost looked like affection. "Well? You're not going to keep the boy waiting, are you?"

"I … no," Sherlock said, stammering a bit as he tried to find his metaphorical footing … and, really, he had never understood before, when people talked about earth-shattering news, because that was just illogical, and yet this news—John had a son—was such that could change, well, everything, and suddenly the world didn't seem quite as steady as it had been ten minutes ago. Focus, he told himself, forcing himself to look at the child with his blond hair and dark brown eyes—eyes he couldn't have gotten from John or Clara, so no, John had not merely been a sperm donor for his gay sister's family. Nor was John Watson a man to lightly eschew his responsibilities. It would have been uncharacteristic of him to have a child and then join the army, but going by the time-frame he knew, the years of service, and Ian's age…

"She died? Your … wife?"

"What makes you think we were married?" John asked, amused challenge in his eyes.

Sherlock thought blurting out "because it's you" wasn't quite what John was looking for, even though it was true. They'd only shared a flat for a few months, but Sherlock had known of John's strong moral fibre since the night he'd shot the cabbie. "Because you're a man who cares deeply about family," he finally said. "But you also live up to your responsibilities. You would never have left for the army and left a child behind unless he was being cared for by his mother."

John looked faintly disappointed, and judging by the way Ian snuggled up against him, he had missed the mark. "Not quite," said John after a moment. "Mary didn't discover she was pregnant until after I'd enlisted, which is a story in itself. I was overseas when Ian was born. Mary … died … of complications. Harry and Clara wanted a baby, though, so … they took Ian while I continued with my military service. He was happy with them and I wasn't ready to come home yet, and it all worked wonderfully until a year or so ago."

"When they separated," Sherlock said, watching the stricken look on the child's face.

"And then I…" John glanced down, and then said, "I had to come home, but I didn't have a house suitable for a little boy, did I, Ian? And they were trying to make things work, so we all agreed to leave things as they were."

"Except Harry's started drinking again."

John nodded. "And that's the one thing Clara won't put up with, and that makes things difficult for Ian here, doesn't it, my lad?"

His son nodded. "They fight all the time, and Mum naps a lot."

Meaning drunk and unconscious, thought Sherlock, as he wondered what this was going to mean for them … for him. He'd finally found not only a decent flatmate, but a friend, but he knew John … and John was not going to let a little thing like a congenial flat keep him from providing a secure home for his child. If the prior arrangement was falling apart, John was going to have to step up, and how was that going to affect them?

Because, watching the two of them on the couch, Sherlock only now realized how little he wanted to be alone again.

#