In some cases, it could even be a new acquaintance who wants to break the ice in a rather unique way. This person might not know Leo too well but still decides to play a harmless prank like changing the labels on his food containers in the fridge. So when Leo goes to get his lunch, he ends up with something completely different than what he expected.
His friends are the most likely ones. They know his habits and routines well enough to pull off some great pranks. For example, if Leo is always punctual, they could set his alarm clock wrong to make him late.
Mario and Luigi are the most likely. They are always looking for ways to outwit Bowser, and pranking him would be a fun way to get back at him for all his evil deeds.
Fred and George Weasley are very likely candidates. They are known for their love of pranks and their mischievous nature. They might see pranking Dumbledore as the ultimate challenge.
Well, in this fanfiction, Leo could be pranked by having his clothes swapped while he's in the shower. So he comes out thinking he's going to put on his normal outfit but instead gets something completely outlandish. Another possibility is that his friends set up a fake lottery win and then tell him it was all a joke.
Sasuke is a likely target. He's so serious all the time, and Naruto would find it quite fun to break his stoic demeanor with a good prank. Another one would be Sakura. She can be a bit hot - headed, and Naruto's pranks on her could lead to some really comical reactions. And of course, Kakashi. He's always laid - back, but Naruto might want to test his limits with some crazy pranks.
Obviously, his brothers are very important. Donatello would be crucial as he could try to diagnose Leo's illness. Raph would be there to provide protection and strength if any threats come while Leo is vulnerable. Mikey would be the emotional support, trying to keep Leo's spirits up.
Maybe it's a new villain in the fanfiction. Some powerful and evil character who sees Leo as a threat to their plans. This villain could use their unique powers or weapons to harm Leo. For example, a villain with the ability to control electricity could zap Leo and cause internal injuries.
It could be an enemy. For example, a rival in a competition or a villain who has a grudge against Leo.
He might also find some allies. Leo can look for friends or even adults who can support him. If he has a good friend, they can walk together and the bully might be less likely to target him. And if he tells an adult like a teacher or a parent, they can take steps to stop the bullying.
A wise old wizard in the story could be a main character. He has the knowledge and power to potentially reverse the spell on Leo. He guides Leo's friends and family on their quest, providing them with clues and magical items that are needed to solve the mystery of turning Leo back.
Raph usually gets really angry. He blames himself for not being there to protect Leo or he gets mad at the enemy who hurt Leo. He'll be the first to want revenge and will be very protective of Leo while he's injured.