Hello friends, thank you for taking the time to look at this! I've been thinking about this idea for a while. I will try my absolute best to make sure things line up with both shows in terms of possibility and big canon events. I based the lecture off of Prof. Brian Cox's lecture on the universe (which is one of my favourites please watch it) so I hope the atmosphere is alright there. I didn't really take anything but the topic from that lecture but I recommend it anyway. PLEASE TELL ME if you see I did anything wrong with the characters or if I missed something in a plot or if something doesn't make sense etc. because I really need the feedback.

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Reid sighed and closed the door behind him, disappointed in himself for getting so tired to easily. He could go days without sleeping, better than any human, but he was failing as a Time Lord.

Reid. The Doctor. Spencer Reid. Doctor Reid. He wasn't sure anymore. He looked around the apartment that was the same size inside and out and was disappointed in that, too. He was a disappointment.

How many years had it been? He couldn't remember. 'Eidetic memory'. He snorted and tossed his messenger bag to the side of the door. That was the only thing he had left that was bigger on the inside. He hardly used it for anything-it was more of a comfort than a utility. He was proving to himself that he hadn't given up on the hope that he could get back to his real life, not that this one wasn't real. Not that it wasn't good. Great, even. Fantastic.

He supposed he couldn't blame anyone for his regeneration into a child. Not much he could do with that but land in a place according to his accent and stay there. The only problem was the rough landing. He couldn't move around as easily when he was, what, six? The crash had been devastating. Years later he still wasn't allowed in, and he leaking vortex energy had made the only woman kind enough to take him in, for lack of a better word, crazy. He was thankful he could stop that problem before something devastating happened. His 'father' was gone so often that he hadn't been affected almost at all, except that what had happened to his 'mother' tore the family apart. The TARDIS felt bad about it after she was told. She's kept her doors deadlocked since then. And now the Doctor was stuck here as Reid, and that was okay. But he wanted to get back. Sooner or later the team would notice he wasn't ageing like them. Gallifreyans aged like humans until fifteen years of age, which he had since passed. Perception filters came in handy when things like that didn't line up. Filters for physical objects were easy enough, but for ideas, those took a while. He had finally done it at about seventeen, not too late. He could still hardly believe that he went from so old to so young in one regeneration. He hoped the trend wouldn't continue. He didn't want to be eighty and then two. It's like the new regeneration energy provided to him was faulty in some sense. He knew the rules well enough... he would just have to deal with what he was given.

This body wasn't the worst it could be. Attractive enough, in his opinion, but he amped up the awkward to make sure to avoid romantic relationships. It was a mistake to befriend coworkers. He didn't know if he could leave them. He didn't know if he could keep lying to them. There would come a time when they were all dead from age or the dangers of the job and he was still twenty and working.

He had to get the TARDIS fixed before he got too far in this made up life.

He hadn't been too paranoid before today. It seemed like everything could keep going as it was forever. He would keep getting PhD's, keep saving people, keep living, almost like it had been. Until today. Today.

It had been a rare moment where they were all together and not stressed about a killer or psychopath or kidnapper or even paperwork. It was a nice lunch. (He ate only when he was being observed, though he didn't really need to a lot of the time). It was a casual discussion about childhoods. Reid listened and didn't share. He had true experiences and lies all laid out in his head, but he kept those to himself if he could help it. The discussion shifted to age, and then to how old everyone was when they got into the BAU. All eyes turned to the 'boy genius' and he gave his answer, reigning as the youngest and smartest among them.

Morgan could be such a pain. He noticed things. He kept a close eye on people he cared about, and that included the 'baby' of the team. He commented that Reid still looked as young as he did on his first day. It was a joking remark at first, but slowly everyone realised how true it was. How scarily true. He was meant to be in his thirties now, but he could still pass as a teenager if need be. He didn't think they would notice. Of course they would notice. Profilers notice things, it's what they do.

As soon as the humour faded from the teams' eyes he was under scrutiny. Of course no one could guess. They would never guess. But the suspicion was a bad thing anyway. Worse than that was the slap in his face: he was already noticeably not ageing compared to them.

He always forgot how quickly humans seemed to change with age. One year difference could be detected. He was estimating he could go for about twenty or so years without anyone questioning or noticing. He was dead wrong. Not even half the way through the time he had allowed himself and already...

There was a knock on his door, then a pause, and a ding-dong like whoever it was had only just found the doorbell. Doctor Reid shook his head free of his intruding thoughts and went for the door, jumping over furniture with disregard for anything permanently placed.

One would think someone like him would be more careful with who they opened the door for, but he swung the door open with the momentum he had collected from bounding across the room.

Rossi stood in the hallway looking confusedly at something on the wall beside the door and pointing to it like he had just had a revelation.

"You have a doorbell." Rossi nodded along to Reid's set tempo and let his accusing hand drop. Reid used his free hands to motion acceptance of entry, and Rossi happily obliged, taking in the small room as he entered. Reid couldn't help feeling profiled.

Rossi looked at his bag on the floor and huffed. "You treat that bag like your child yet you leave it on the floor." He looked at Reid, not missing the blood rushing to his cheeks and his bobbing Adam's apple. "You wouldn't make a very good father."

Reid managed a humourless laugh, though he meant it to come out more light-hearted than it appeared.

"Sorry." Rossi said casually, "I didn't mean anything by it."

Reid nodded in understanding. "It's alright. I know. I just disagree is all."

Rossi swiped some dust off of the tops of some books that didn't fit on the shelves absently. "Do you want children?" He paid Reid little more than a glance, trying to make the question less intrusive than it was by eliminating a penetrating gaze.

Standing in the middle of the room and turning on the spot to watch his guest, Reid answered, "Yes. Eventually."

Rossi almost laughed. "Because you're too young now?"

Reid shook his head though Rossi wasn't looking. "No, I just want to do it with the right person." He thought of Susan now, how he had failed as a grandfather. And Jenny, though his time with her was only brief, how he couldn't let her see the stars with him. "I want to do it right." He corrected more generally.

Rossi stopped prodding around the apartment and drifted over to Reid in the middle of the room. "That's a good idea. I didn't have that patience. But you should watch out, my friend. The clock runs out for us all, and yours is ticking. How old are you now?"

Reid swallowed. He could feel Rossi leading in to this conversation from a mile away. "Thirty-one." He answered through uncontrolled nerves.

"Time is ticking on." He warned one last time, then took a breath and broke his stance, signifying the end of his cryptic comments. He picked up Reid's bag (to which Reid tensed and made himself ready to charge for it) and offered it to it's owner (to which Reid relaxed and accepted it).

"Shall we?" Rossi opened the door like it was his to open. Reid shouldered the bag and grabbed the strap for security, nodding and taking a needed breath before leading the way out.

The car ride was almost enough to make Reid regret making plans with Rossi to go to the lecture. It probably wouldn't be anything he didn't know, he just enjoyed listening to things being rephrased, presented, and enjoyed watching other people react and questioned. He loved the atmosphere at lectures. Rossi had asked to come along.

When they got there barely on time, little of that was left for conversation, so they made a bee-line for the lecture hall and sat where they would hopefully be able to see and hear fairly well. Only five minutes after sitting down, the hall had miraculously filled and the projector displayed an image of the earth from space. Just that made him giddy.

The speaker came out and the hall fell silent. Reid was on the edge of his seat, literally, and near squealing with delight.

"I want to talk about the universe..." Came the voice from the speakers. Reid started bouncing in his chair.

"Calm down or you'll explode." Rossi whispered his warning which might not be too far off. He was quickly ignored and told to "Watch, watch!" as if something immediate were to shock him, but only be observable for a second to be easily missed.

Rossi learned about one thing during the lecture: Reid could talk really fast. In between the speakers breaths the kid would elaborate and provide insights into whatever had just been explained before Rossi had a chance to think what was happening. There wasn't a time when someone wasn't explaining the physics and quantum mechanics of the universe to him for a straight hour and a half. Rossi didn't think of himself as easily mentally fatigued, but he was tired from just sitting next to someone so permanently enthusiastic as Reid for this long.

Just as Rossi was about to get a word in, as the audience was standing, Reid was tapped on the shoulder by a man who had been sitting behind them the whole time. He could probably hear Reid's incessant flow of knowledge, Rossi thought. He was ready to back Reid up in a fight if need be. Instead of a challenge, the man in the long, black trenchcoat smiled and was friendly.

"Hey, I overheard you during the lecture and you really remind me of this friend I-"

"Jack?" Reid seemed shocked to know someone, Rossi thought.

The trenchcoat man, Jack, seemed even more surprised, taking a second to respond.

"Doctor?"

Rossi was still skeptical of this person. Reid didn't really have 'friends'.

"He has a name." Rossi challenged.

"Oh, really?" Jack responded to the FBI agent, then turned to his old friend. "Doctor who?"