Written for the Fanfiction Perfumers Competition; for the Rubik's Cube Challenge; for the Crazy Eights Challenge; for the Create-A-Potion Challenge. This is, quite evidently, a superhero!AU, as assigned for the Rubik's Cube Challenge.
It was a myth, he decided once in his fifth year of school. He just wasn't a superhero.
What was so special about him?
(Oh, right - nothing.)
As a child, he'd thought that he was a defective - that he hadn't inherited his parents' powers. After all, all the other superkids his grandmother knew could breath fire or shoot lasers out of their eyes. So when a letter materialized at the Longbottoms' breakfast table inviting Neville to attend Hogwarts School of Superpower Mastery, he had thought there must have been a mistake.
(Really, he was the mistake.)
This mentality didn't change throughout school. Upon arrival, he learned that he was the only one with absent powers. The rest of the children there knew exactly what they could do - they could take on the abilities of different animals or breathe fire or see through solid objects. One girl knew everything that ever was and would be about the universe and didn't even have superheroes for parents. One boy had nearly been killed by a supervillain when he was a toddler but had defeated him by sucking out his soul.
(Neville could feel sorry for himself, and that was the extent of his powers.)
Over the years, school continued to worsen. While everyone else kept learning how to be brilliant and use their superpowers in the best possible ways, Neville still knew nothing. He wasn't anything. The school's professors would encourage him and tell him he could do better, but it was obvious they didn't care. He usually caught a hint of a patronizing tone in their voices when they told him that "he could do it" and "sometimes powers take a while to make themselves evident."
(Did "a while" mean "forever"?)
Several kids in his class befriended him, but they seemed to pity him more than anything else. One boy often complained to him about his superpower, invisibility: he loved attention, and what was invisibility going to do for him?
(Surely, Neville thought every time the boy brought it up, invisibility would do more for him than lacking any power at all.)
At the end of his fifth year, the godfather of one of Neville's friends was kidnapped (or thought to be kidnapped, at least), and somehow Neville found his way to the Ministry of Superhumanity to save him with the boy and four of his friends. One was kind to him - a younger girl who had super-strength and could sense others' personalities and superpowers. He rather liked her. But of course, unavoidably, while the girl fought against the supervillains with her fantastic power, Neville was stuck with nothing. For the entirety of this superhuman battle, he knew he was the most useless he had ever been.
(That wasn't a change from the rest of his life, though, right?)
For some reason, though, his grandmother was led to believe that he'd been some great superhero in the battle, and upon his return home from school she hugged him tightly and wouldn't let go for what felt like hours. "You're just like your parents," she said in her tears.
(Neville's parents had been courageous heroes who defeated countless archvillains until one horrifying man who destroyed his victims' memories defeated them.)
Was it the belief that he might be like his parents that did it?
(He found out when he returned to school the next year that he wasn't, in fact, a defective. Neville Longbottom actually had a superpower: he could change his molecular makeup into anything he wished.)