Sherlock cautiously walked to the door and paused for a minute, listening. John had stayed outside for a while, sometimes banging on the door and yelling, sometimes knocking and pleading (Sherlock could only guess how much that last one had hurt his pride). He'd tried to distract himself by updating his ash index, but he'd invariably ended up reading John's blog, at which point he slammed the laptop shut and resigned himself to curling up in a ball. John had eventually stopped knocking and walked away, and Sherlock had heard him go downstairs. He might have heard the front door open, but he couldn't be sure.

He unlocked his door and peeked out. The kitchen was empty, the flat oppressively silent, and he was forcibly reminded of John's wedding and the loneliness it had entailed.

Perhaps that was better, he thought. At least John was happy. Now he's sad and angry and I'm the reason for it.

The thought made his gut twist painfully and he dropped into his armchair. He checked his phone to several texts from Mycroft, detailing the angry messages he'd received from John in the past hour. Sherlock couldn't stop his mouth from lifting into a smile at the screenshots. John had used some very expressive phrases, including moron and heartless and if you don't tell Sherlock that you were bullshitting with that 'caring is not an advantage' stuff, I'll break your umbrella.

Apart from that, there were several missed calls from John and a text saying 'call me'. For a few seconds, Sherlock's fingers hovered over the keypad, and he tapped out 'please come back'. There was a moment when he imagined pressing send, then John would come back and they'd hug and he'd explain everything.

He erased the message and switched off his phone.

They're just emotions. Chemicals in the brain which can be controlled if need be.

But he'd studied enough chemistry and biology to know otherwise.

He tuned his violin, but ended up playing such a mournful melody that he depressed himself further. Flinging it down on the armchair in disgust, he picked up a pile of post-its, intending to update his case notes. But his brain was too muddled, and even thinking about Rosie getting kidnapped was painful. He made himself some tea, then realized he'd made two cups out of habit. Slamming the cups down in frustration, he grudgingly admitted that he couldn't tune his emotions out this time.

One day, he thought helplessly. You get one day to wallow around like a lovesick fool.

The lights seemed too bright, so he switched them off and curled up on the sofa. His arm brushed against something soft, warm and instantly recognizable, and he pulled it out with a sinking feeling. It was one of those ridiculous jumpers, the ones which John somehow managed to look endearing in. He ran his fingers over the knitting pattern and recognized it as the one John had worn to their first case. They'd both been so alone and averse to offers of help, but so entirely willing to throw their lot in with each other. He still didn't know what had gone through his head when he saw John for the first time and decided, that's him, that's my new flatmate. He definitely hadn't expected to find a companion, a friend, and a lover.

How could I have expected it? I make enemies on a daily basis. Nobody who comes in contact with me can possibly be safe. My love only endangers people and turns them into weapons - against myself.

He hugged the jumper to his chest and wishing that he had had the foresight to store away just one dose of morphine, resigned himself to a night of misery.

For the most part, single parenthood hadn't been all that hard on John. Rosie had a lot of doting godparents and a loving aunt, all ready to take care of her at a moment's notice. Once Sherlock got the hang of what he called the 'baby business', he had been a huge help. John hadn't expected him to be so patient or so good with Rosie. In fact, even saying he was a single parent felt immoral. Sherlock had been there all along.

Sometimes, John thought about Mary's death and felt strangely betrayed. We were supposed to do this together, he thought bitterly, pacing up and down Mrs Hudson's living room with Rosie in his arms. She should be here, helping me decide how to deal with this.

He couldn't believe how close he'd come to losing Rosie, but it had convinced him of the seriousness of the situation they were dealing with. He'd learnt from experience that whenever someone targeted him or his family, it was usually an indication that they would stop at nothing to tear Sherlock down. Moriarty, Magnussen, Eurus...they'd all followed the same technique.

There was a tight feeling in his chest, and try as he might, he couldn't get the muscles in his arms to unclench. He didn't believe Sherlock's 'caring is not an advantage' excuse one bit. Still, it was probably a good thing that he'd left him alone for a bit, given him some space to think things through. All that remained was deciding where to go: outside to a different life, or upstairs to Sherlock.

In the end, there really wasn't any choice.

Sherlock had thought he would never be able to sleep again, but he drifted off eventually, only to be roused by a nightmare. He sat up with a sharp cry, automatically reaching out for John, but there was no one to comfort him - only the dark, oppressive stillness of the night. He took a deep breath, willing his heart rate to come back to normal.

You can handle this, as you did for years before you met him.

He curled up on the sofa again, sore and uncomfortable, but unwilling to sleep on the lonely bed. There was something strangely suffocating about the darkness and the silence in the flat. Not for the first time, he wondered if he was making a colossal mistake, and stretched out his hand. He picked up his phone and switched it on.

Weak.

He stopped himself at the last minute and flung it across the room instead. It hit the wall and bounced off, upsetting one of Rosie's block towers. He heard the screen break with a satisfying crack.

There. This way you won't even be tempted.

He turned away and buried his face in the jumper, lulled by the comforting mixture of smells which were so uniquely John. He spent the night in some dreamland between slumber and wakefulness. By the time the first rays of dawn penetrated the room, he had given up on getting any sleep. He sat up and suddenly froze, for he had heard footsteps on the stairs, and then the door creaked open.

John peeked in, and as on every other morning, his hair was a perfect rat's nest. He caught Sherlock looking and nervously tried to flatten it, and Sherlock was forcibly reminded of a conversation they'd had many mornings ago.

How do your curls always stay in place? I could use an entire bottle of product and my hair would still be like...this.

Your hair's perfect, John. In any case, it doesn't matter, you don't have many years of a full head of hair left. Your natural process of ageing will be faster than most, thanks to stress and PTSD. Your joints, too -

So you'll still love me when I'm bald?

I hope you'll stay with me for long enough to find out.

He caught John's eye for a long, painful moment, then blinked and got up. "You can pack your things. I'm heading out. I won't be in your way."

John crossed the room and took his hand.

"Sherlock, please just talk to me. After this - if you still want me to leave, I'll go. I won't bother you again, if that's what you want."

"That is what I want. Nothing you say can change my mind."

John kissed each of his hands by turn, not letting go of them even when Sherlock tried to pull away. "Let me try."

Sherlock felt something inside his chest melt.

It can't hurt to hear him out, can it? He deserves closure.

He shrugged and led John to the kitchen table. Deciding it was probably best to keep maximum distance between them, he sat across from John, folding his legs resolutely under the chair. It wouldn't do for them to start playing footsie.

"I thought you'd be gone by now." he said, trying to keep his voice even.

"Why?"

"I told you. I'm a machine. I don't feel."

"I'm not falling for that again, love. I'm not leaving until I know the real reason why."

Sherlock saw the resolute look in John's eyes and knew that he meant it. "Then deduce me, Doctor Watson. I'm sure you've learnt something over all these years."

John studied him, and for a moment, his sadness was replaced by the ghost of a smile.

"You didn't sleep last night." he said. "Which means you aren't happy about me leaving."

"Hmm."

"You think Rosie getting kidnapped was your fault, and you want me to take her someplace safe."

Sherlock wanted to deny it. He wanted to lie and tell John that he really didn't care about him, because that would surely get him to leave and then he would finally be safe. But then John leaned across the table and took his hand, and he felt his resolve dissolve.

"Not just Rosie. You, too." Sherlock said, "Over the last few years, I have seen you wrapped in Semtex, targeted by Moriarty, set on fire, tranquilized by my sister, and chained to the bottom of a rapidly filling well. That's without even counting the car accident and everything that's happened since then."

"So you still think the car accident wasn't an isolated incident?" John asked, suddenly curious, but then shook his head. "No, wait, not important right now. The point is - you once said 'alone is what I have. Alone protects me.' You lied. Alone doesn't protect you, it protects other people. "

Sherlock felt his face colour, but he knew there was no turning back now. "Am I really that easy to read?"

"No." John admitted. "At first, I thought I had messed up, or you were tired of the whole relationship thing. You see, I didn't...I didn't think you cared about me enough to want to protect me."

"John, that's a truly ridiculous thought to have."

"Yes, well, I am a ridiculous man, redeemed only by the warmth and constancy of your friendship."

Neither of them could help but smile.

"The thing is, Sherlock - you're right. I don't care how much danger I'm in, you know that, but I can't say the same for Rosie."

Sherlock looked down at their joined hands. He didn't have the willpower to take his away. This could well be the last time I get to do this.

"Let's face it." John continued, "I'm already a marked man. Even if I move away and cut off all contact, it won't save me from being used against you. Everybody knows how much we mean to each other. There's no getting around that."

"But Rosie - "

"Rosie won't be better off." John interrupted. "Mary made enemies, too. Lots of them. This, right here, with both of us - this is the safest my daughter will ever be. She's not just my daughter, you know - she's our daughter. She needs you. She needs both her fathers to look after her. We haven't done a great job recently, but for her sake, I'd be willing to try again."

Sherlock looked back up, disbelieving. His throat was dry and his eyes suspiciously glassy. "But - are you sure about this?"

"I am. You aren't."

"No, I'm not." Sherlock admitted. "Are you really saying you want to stay with me?"

"Of course I do. What's bothering you?"

Sherlock shrugged nonchalantly. "Just a thought."

John raised an eyebrow at him, clearly not buying it. There was a long pause.

"You already left once." Sherlock finally said. "You left me in Culverton's hospital, when you dropped off the walking cane. Granted, I had anticipated and even banked on the possibility - "

"Sherlock." John said, gripping his hand tightly to shut him up. "Stop. That had nothing to do with you being the prick that you always are. That was me, all me, and I was in a horrible state of mind. By the time I got home from the hospital, I'd really just had enough."

"Enough of what?"

"Enough of myself and what I was doing to you."

"You haven't done anything to me. Nothing bad, at least."

"Let's see." John said, taking his hand away and getting up to pace the room. "First, my wife shot and almost killed you. You killed Magnussen to save her, then almost got shipped off to god-knows-where. On top of that, I blamed you for her death, iced you out and then hit you. When I dropped off the walking cane, I decided not to see you again, because whatever I do - I just end up hurting you."

"I - I thought you were tired of me interfering in your life and smudging everything up."

"Well, the great Sherlock Holmes miscalculated. I left for your sake, not mine. I could never leave you of my own free will. Never."

It was Sherlock's turn to get up and take John's hands, massaging his fingers until they unclenched, squeezing them reassuringly. He didn't know which one of them it was for.

"Stay." he said simply, then leaned forward to cup John's face in his hands and kiss him. Something in his chest flitted back to its usual place, and his muscles didn't feel quite so tight anymore. He paused to close the small pocket of space between their bodies, foreheads close enough for their eyelashes to brush.

"Stay with me, John Watson."

John pulled Sherlock down by the collar and stretched up, almost on tiptoe. His lips ghosted past Sherlock's mouth, the ridge of his nose, his cheekbones, finally coming to rest on his forehead.

"Always."