He didn't tell anybody he'd signed up for the trials.
Considered borrowing his Dad's helmet when he went to see the Professor and asked to be excused from the team for six months. Told him he wanted to go travel for a bit, see more of the world. Spent an hour beforehand staring at travel brochures and thinking hard about the places he would go and the things he would see, threw those thoughts as hard as he could during his chat with Xavier and hoped that the noisy blur of his mind was too much for him to find the idea that he would actually be staying, and letting someone experiment on him. It had seemed to work.
Angela was upset that he didn't want to take her with him. He wondered if he should try to persuade her to sign up too, then they could be normal together. He decided one person knowing was one too many, and didn't.
He told his Mother he had to go away for training and she wouldn't be able to contact him. That was the only part he felt bad about.
It wasn't one little shot after all, but a course of three. One a month, then six weeks before he'd go back and see how his mutation was reacting to the experimental gene therapy. It didn't cost anything. The labs knew they needed all the willing subjects they could get, and chose not to charge. He rented a tiny apartment near the labs. Nobody took any notice of him or tried to make friends. It was quiet but it was good enough.
After the first shot he'd gone back to his shoebox apartment and slept for sixteen hours straight. Woken by a stabbing pain that he'd soon worked out was just his body protesting at not getting fed for all that time. Ate, showered, went back to bed and slept until he couldn't ignore the hunger anymore again. Did a lot of pacing, a lot of thinking, a lot of feeling crazy and cooped up, but he stuck it out. Wished he could get drunk enough to stop the whirring thoughts. Got pains in his legs and hips from not going for his usual runs. Ignored it, the labs having told him that the less he used his gifts the better the serum would take. Wished he could call his Mom when the pain was particularly bad. Didn't call anyone.
The second month he'd done an awful lot of vomiting. Tested out his powers and found that his top speed was definitely slower than it had been. Felt dizzy a lot, tried not to stand up too much. Watched a whole lot of daytime TV and didn't get dressed for days at a time, only changing out of pyjamas when he had nothing left to eat in in the apartment. Ate a lot less anyway, felt sick most of the time. Couldn't stand the thought of his usual junk food diet. Did a lot more sleeping. Lost twenty pounds. Didn't really care. His head had got quieter, less like an out-of-control fairground ride and more like what he thought normal people's minds must feel like. Tried to enjoy being able to rest and concentrate. Didn't particularly feel like concentrating on anything anyway. Wanted to call Angela and tell her he was doing fine, didn't want her to come find him. Got horrendously drunk on vodka one night and had his first genuine hangover. Decided he never wanted to look at alcohol again.
After the third visit to the labs he'd gone for a run. Got out of breath for the first time in his life. Told himself it felt good to be exhausted and dizzy after that little exertion. Noticed strands of white-blonde coming through in his hair. Bleached the rest to match. Couldn't really get used to the sight of himself blonde and stopped looking in the mirror. Thought he should maybe get some new clothes now that all his old ones were hanging off him, figured his sweats had a drawstring and just pulled that in tighter instead. Read the entire works of Dickens, enjoyed being able to sit still and do so. Slept an enormous amount, less and less frequently woken up by hunger. Bought some protein powder, which was easier than forcing down food he didn't really feel like he wanted. Went down to 80lbs. Missed running, told himself that once his body settled down and he was used to the serum he could build back up to it – just normal, sensible running. Was surprised to find that a normal human speed of thought felt surprisingly and unpleasantly like being drugged.
Couldn't stay awake for much of the long weeks after his third shot, waiting to see how he'd react to the treatment. Slept on the sofa because the bed was too far away, made himself drink a protein shake when he got crippling stomach cramps, felt sick after and wanted to throw up. Stopped himself doing so most of the time. Took codeine for the agonising pain in his joints, wondered why he was getting that when he was hardly even walking around, let alone running. Enjoyed the fact that painkillers were working on him for once. Decided that normal was actually quite painful and missed the resilience of his mutant physiology. Discovered that he could get his hands almost entirely around his waist and had no muscle left on him and thought he should maybe see a doctor. Didn't see a doctor. Didn't even recognise himself when he'd finally uncovered the mirror to take stock – overgrown platinum-blonde hair down to his shoulders in dry tangles, punched-in eyes with huge puffy shadows underneath despite all the sleep he was getting, razor-sharp cheekbones. Wondered if Angela would still like him now he looked like a homeless drug-addict.
Missed her. Missed his family. Missed his life. Missed Hank and Charles and the Mansion and feeling like he could do anything. Stopped taking the mutation-supressing medication the lab had given him. Bought a treadmill and started trying to work up to a run again.
The pain eased off, which was good because the codeine had stopped working. He was less tired. He didn't feel like sleeping all the time. His thoughts started to clear and speed up. He made himself eat an entire pizza, then made himself lay on the sofa and watch the evening movie, and ignore his bulging, overstuffed belly grumbling uncomfortably at him. He called his Mom and told her he was okay. He didn't go back to the lab to be assessed again. Worked at the treadmill until he was exhausted and rewired it to go at something like a decent speed, and ate doughnuts by the dozen and tried not to throw up. Cut his hair himself and was glad when it had started to grow through silver again, wondered why in the hell his mutation changed the colour of his hair anyway and thought of his green-haired little sister and cried and made himself feel thoroughly nauseous but considerably less sad by eating an entire pint of ice-cream.
He ran every day and needed less and less rest between bouts on the treadmill, looked forward to seeing his friends again and hugging Angela and his favourite jeans fitting him and to getting back to training. Enjoyed his mind starting to whir and wander the way it always had done and wondered if he would get away with telling Hank he'd had dysentery or something and was glad he'd found out how dull and limiting normal really was and pushed himself as hard as he dared. Hoped that the treatment wouldn't have any permanent effects now that he'd stopped it and hoped that his father would never find out because he would definitely kill him, came to the conclusion that he actually quite liked being him if the alternative was being tired and wasting away and not wanting to do anything and longed for the day he could go for a proper run again.
Finally he decided he couldn't wait any longer and went out and was thrilled to find he could speed again. Enjoyed the freedom of whizzing past faster than anyone could perceive him and the feeling of gravity tugging futilely at him and flouting the laws of the Universe and being himself again. Stole a box of Little Debbies and went to bed that night with the worst stomach-ache he'd ever had but felt better for the sugar and couldn't wait to go running again. Was glad that he was different and amused that others couldn't do what he could and felt a little bit sorry for those humans who would never know how good it felt to break the sound barrier on foot.
He gave up the lease on his little apartment and went home, and enjoyed Scott teasing him about the blonde tips in his hair, and hugged Angela and Jubilation and Kurt, and didn't whine about Hank putting him on a strict diet plan and was finally happy to be a Mutant, and didn't even mind the Professor telling him that he'd had to find that out for himself, as long as he didn't tell his Dad.