John was surprised to find how roomy Sherlock's mind palace was.

He's obviously heard the word palace, and figured it had to be grand and such, but he didn't think it would have such depth. There were floor and wings, all filled with carefully labelled rooms. Nothing was out of place.

But he was getting ahead of himself.

It had taken a long time for him to get out of his own room, which was massive. It looked like an old library, packed with bits of information, facts, sweater preferences, the way he took his tea, how to tell when his leg hurt.

It amazed John. He'd known Sherlock was collecting information on him, but he didn't expect it to be so meticulously collected and catalogued.

It was astounding.

He was still ahead of himself. Perhaps. Was he?

Perhaps not. It had taken him a while to come to the conclusion of where he was, and even longer still before he realized what happened.

He'd woken up in the library. He'd had no clue about why he was there, or even how he'd gotten there. It was only by wandering around and looking at the things that he realized it was his room. Or at least it was all about him.

That was how he realized he was in his room of Sherlock's mind palace.

He didn't know how long it took him to realize that, or how long it took him before he left the room, after pouring over every scrap of information, facts about himself that he hadn't even realized. Time didn't seem normal there, but how, he couldn't quite say.

He only realized after reading through his jumper catalogue that the room had a door.

He stared at it for a while, curious as to where it might lead. If he stepped out it, would he fall into Sherlock's brain? Who knew what else was out there. Was the rest of it organized this well, or was John in some way special?

Perhaps the rest was just a void.

But he couldn't stay in his room forever.

So he opened the door and found a hallway on the other side.

It was when he stepped out that he realized how gorgeous it was. A genuine palace. Marble floors in the hallways, each room carefully decorated to match its purpose. There was a room containing samples of however many different types of tobacco ash there was. Another contained perfume samples for easy identification.

He worried about getting lost, but since he wasn't going anywhere, he supposed it didn't matter.

John found a room where he could he was Sherlock was seeing. It was labelled eyes.

He was staring at himself.

There was an audio function, and he switched it on.

"There is evidence of minimal brain function. He wasn't breathing on his own, so a machine is helping him. It was a rather severe head injury that he suffered."

He detailed surgery, but the hearing faded out at that point, and John realized it was because Sherlock was too focused on the sight of John to remember to listen at the same time.

He did hear the ending though.

"Complete recovery is nearly impossible with this level of injury. I'm sorry, but you have to be prepared for him to have some level of brain damage when or if he does awaken."

"No," John heard Sherlock say. "No. John will recover. He has before. He will again."

John left. He couldn't hear any more.

He wandered the halls.

The Mycroft room was tiny, but cozy. Of course, it was also dusty, like Sherlock hadn't been taking care of it.

Mrs Hudson's room was a physical embodiment of her personality, soft and flowered. John felt safe there, and would often return when he was feeling stressed about his current state (whatever the hell it was) or Sherlock's panic managed to seep out of his carefully designed worry room and spread everywhere.

Lots of other people had their own rooms, but none as detailed or as large as John's.