The sun was high in the sky on the day that Sherlock first fell apart.

It was a particularly easy case. Of course, the police couldn't see what was right in front of their noses but he wasn't about to complain. Not really.

Without cases Sherlock was useless. He couldn't have a normal conversation, so socialising was out of the question. He couldn't resist any chance to find out about the inner workings of any mechanism – biological or technological. He couldn't think, couldn't move - couldn't exist without the cases. Just yet another one of his many shortcomings.

He had to admire the arsonist; he almost missed it – almost. In the midst of the room's charred and smoking remains, with the stench of burned hair and flesh hanging heavily in the air he was distracted enough not to notice the shards of glass on the floor. They were dotted around randomly under all of the grime.

Broken glass at the scene of a fire is not uncommon what with windows exploding under the pressure of the high temperature of the flames. What is uncommon, however, is shattered bottle glass in the centre of thirteen-year-old girl's bedroom. Green bottle glass - the type used for alcohol such as lager.

The rag would be long gone by now. He knew this from personal experience. The heat of the explosion would have rendered it to dust within seconds. But the glass had survived, forced apart but not melted by the heat. He knelt on the ground and picked up several pieces with tweezers, dropping them into a clear plastic bag held by John.

John, who was currently trying not to breathe in through his nose for fear of vomiting. Spectacularly. Even with this effort claiming most of his concentration he noticed the small change in Sherlock's composure before even he himself did. He coughed slightly to get his attention. The detective looked up.

And when he did it was horrifying.

His face was pulled downwards by a frown that seemed to age him by thirty years. Lines criss-crossed across his forehead and around the corners of his mouth. His eyes were dead. The usually bright grey irises were dulled with a pain so intense it seemed to emanate from every fibre of his being. He sniffed slightly and sprang upright with such vigour that he almost fell straight back down again if it wasn't for the steadying hand on his back.

"Lestrade-"

There was a sharp tinkling as the glass in the laundry room window broke. His small feet padded along the hallway towards the door concealing the offending noise which had now accelerated into a large crashing wave of crackles and pops.

Like the Rice Krispies advert.

The crackling noise increased further if possible as he reached the door. Then, and only then, did he notice the small rivulets of smoke eking their way out from the doorjamb. He sucked in a great breath to shout for Mycroft but the black fog grasped his throat in a malicious grip –

He coughed slightly before continuing.

"Lestrade the facts are as follows. The girl followed the source of the sound of a window breaking, perhaps she thought it was a kid playing with a ball – does she have a brother? Yes? Okay then there you have it – but what she didn't realise was that it was a Molotov cocktail that had made its way through the window into her bedroom and subsequently-"

-he was still struggling for air when he raced back up the stairs and choked out Mycroft's name before winging it back to the door. The soot filled air pressed down upon him as he reached out for the doorknob, scalding his hand on the red hot metal. Panic rose in his throat pushing the smoke away for a split second and he took a step back. There was no point in opening the door if it would let the fire out quicker, was there? Why was he trying-?

Oh.

There is was again! The small mewling cough of his pet kitten who had obviously made his way into the laundry basket again. Mummy always told him to keep an eye on the small tabby who he had named Harold or he'd get in trouble.

He pushed hard against the weakened wood of the door and was met with a wall of flames that leaped out at him, catching the curtains of the window behind him, effectively sealing off his main exit as the hallway was filled with fire. He grabbed a hold of the scruff of Harold's neck and yanked him into his arms.

"Sherlock!"

Mycroft was calling him frantically, his usually unshakable persona slipping as he was met with the blazing inferno that was quickly moving up the hallway towards his younger brother-

His eyelids fluttered closed against the memory. He could almost feel the heat of the fire and hear the beams falling, weakened by the conflagration's ravenous jaws, cutting him off from safety.

He remembered the fire of course. He remembers standing outside waiting for the fire fighters to put it out. He remembers going back into their house and standing in the middle of the wrecked hallway wondering what happened.

"Sherlock." John was talking again, his hand brushing down the ash from his expensively suited shoulders.

"But-" He coughed again, "But she didn't realise about the fire until it was too late. There must have been something in here she wanted to save, a pet, sibling – something." Lestrade nodded, absently taking notes. He had obviously noted the change in Sherlock's behaviour himself, but saw fit to leave John to it.

"Any idea of who did it?"

"Father's mistress of course." Sherlock muttered and swept from the crime scene, not stopping, not looking at John until they made it back to Baker Street.

Sherlock didn't understand. How could he have deleted such an important piece of information from the major crime of his childhood? He discovered the fire, nearly got trapped in the flames, and nearly died trying to save his pet cat. This was back when Mycroft's interfering ways seemed brotherly and loving. Not manipulating and downright annoying.

It was simply a sign of Sherlock's defective brain function that he'd repressed a memory so huge and interesting just for the sake of avoiding a few months of pain. He did not know whether the girl's father's mistress had firebombed her room. That was his own story that he'd projected onto another incident, but it was probably true.

John tried to get him to talk but he kept his mouth firmly shut. For five days he tried to grasp at the edges of long lost memories, trying to piece together a story he had long since forgotten. It was like trying to remember a single note in the midst of an entire composition or the name of a single star in the entire universe.

And once he'd remembered he locked it away. He put it away for future reference. It may come in handy to empathise with victims some time. Or at least he tried to tell himself.

He spoke to John once about it. Just once, three weeks afterwards. He was lying on the sofa watching daytime television when it struck him just how much this must have intrigued John – seeing the usually stone hearted detective break down in the middle of a crime scene must have shaken him up. So he decided to leave him a note. He didn't know whether he got the message but judging from the cold cup of coffee next to the sofa when he next woke up…

The note held only six words.

She was thirteen. I was seven.