It took a while to diagnose Charlie's problems; what thirteen years old boy isn't moody? But once his parents suspected there was something else going on inside his head, doctors injected a swarm of machines so small they were practically very large drugs, and the machines showed them that, to Charlie's annoyance, his parents had been right.

Brains are like ecosystems, Charlie's doctor explained to him and his parents. Every part of Charlie's brain works, but the way they synchronize and work together isn't the way we would prefer. The system is in a balance of sorts; it's just that it's a balance that results in things like mood swings and insomnia.

The doctor hadn't mentioned the nightmares, but Charlie suspected he knew how bad they were, even if he hadn't told him, or anybody else, how much the night scared him. Probably the machines inside his head had told the doctor the truth. Charlie didn't have insomnia, he just tried not to sleep.

What do we do then? had asked Charlie's mother. Give him medication? His uncle used to take antidepressants.

The doctor had nodded. That's what we would have tried a few years ago, but it takes quite of a bit of trial and error, and even once you find something that works, there are usually side effects. Almost always the side effects are minor compared with the original symptoms, and you can tweak the dosage and sometimes eventually cease the medication, but today we have better tools. We already have nanobots lodged in key areas of Charlie's brain. We are using them to diagnose him, but they can be partially rebuilt to integrate themselves with his brain functions.

Charlie's father, who had seen a lot of horror movies as a teenager, frowned. You mean use a computer to control his emotions?

The doctor smiled. Oh, no. Its like adding a carefully chosen new species into an ecosystem. It will interact with the rest of his brain, send a signal there, dampen a neurotransmitter here, and Charlie's brain will adapt slightly to it while the machines adapt very strongly to him. The end result will be a healthier and more resilient brain, but not a different one, and certainly not one under anybody's control but him. We are only beginning to try it in humans, but we can monitor it very closely and stop if anything looks wrong, so in a sense it's safer than the usual medication.

Using machines they could instantly switch sounded like a safer option than trying medications until they found something that worked, so they modified the nanobots in Charlie's brain to make them able to talk to it as well as listen.

The brain talked and listened to itself, and now itself included both the machines and the software controlling them from a small chip in Charlie's skull. The chip learned from Charlie's brain, Charlie's brain learned from the chip, and eventually they were just Charlie.

The mood swings and the nightmares went away. The chip didn't change Charlie, and nobody hacked them. This isn't that kind of story.

* * *

There's a thirteen years old child waking up from a nightmare, crying. But this is three years later, and she's called Grace.

* * *

Charlie's parents wanted to refuse. Would've, certainly, even to the doctor who had healed Charlie. But he had shown them videos of Grace, and although everybody agreed that it had been a low trick, it was enough to make the parents agree to leave the choice to Charlie.

She has the same sort of device you have, the doctor told Charlie. The device works well; yours too, by the way, you know I'll get an alert if anything went wrong. But the device needs to learn from the brain how to help it, and for some reason it's not able to learn from Grace's. We think her condition is somewhat different from yours, like the same riddle in a different accent, and the device isn't picking it up.

So what do you want me to do? asked Charlie. He wasn't a bad guy, but he didn't want to go to a hospital again, ever.

The doctor told him his plan. It was much worse than what Charlie had feared. Maybe that's why Charlie said he would do it, the way sixteen years old say 'yes' to whatever really scares them.

* * *

Grace and Charlie didn't lie in parallel operating tables, thick cables connecting their skulls. They sat in comfy chairs next to each other while both sets of parents watched. The doctor was telling them again how they had temporarily reprogrammed the chips in their skulls so Charlie's chip would control Grace's nanobots and the other way around, but that was mostly to fill the silence while he monitored everything.

Not that the parents paid much attention anyway. Charlie's were too worried about something going wrong, and Grace's were crying softly.

For the first time in a long while Grace had fallen asleep smiling.

* * *

It took seven sessions for Charlie to train Grace's device. At the end they were close strangers, people with nothing in common except a very important thing much too big to base a friendship on. But she was thirteen, so she had given him a nickname anyway.

Why does she call you that? asked the doctor after the last session, at a time when he and Charlie were briefly alone.

You know, said Charlie, rolling his eyes, like the guy from the movies. The one who can read minds.

The doctor, who had liked the character about two franchise reboots before, smiled. Well, your brain can do something nobody else's can, and you helped her, so she's not entirely wrong about that.

By the way Charlie looked at him while pretending to find him ridiculous, the doctor knew that he would agree to help if he ever asked again.

* * *

He did ask, four times. It turned out Charlie's success had been less likely than they had thought, and his brain's talent to train the device a rare one. Charlie was always enthusiastic to help, and Charlie's parents eventually made peace with it, not without fear, but also not without pride.

The doctor finally stopped asking for his help once the company designed new machines that could learn from any brain; they had figured out how to do that by watching Charlie help others, and in that sense he would always be helping. Charlie had shrugged when told, relieved but hating himself a bit for it.

He kept in touch with the doctor. They never mentioned the returning nightmares. Charlie had known his own well enough to understand they weren't his to begin with; his brain had learned them from the other kids' devices, who had learned them from their brains.

They talked about everything else, mostly about the people helped by the software they had built based on Charlie's brain, pretending it was a coincidence that the doctor always called the morning after a bad nightmare. He was still monitoring Charlie's device, after all.

Charlie hates the nightmares, and feels bad about never telling his parents about them. But if he had told them they wouldn't have let him help. Keeping secrets had been a necessary part of being a superhero, and if he woke up in a cold sweat more often than not... Most retired heroes had scars, and he had earned his helping others.

And he's no longer afraid of the night.