Often, in such a fanfiction, the story develops around the chaos that his transformation brings. Since Inuyasha is now a child, his usual brash and confident self is replaced with a more innocent and sometimes naïve version. This can lead to some comical situations, like trying to fight with a smaller body and less strength. His friends have to keep him out of trouble more than before, and there could be a plot where they search for a way to turn him back to normal.
In these types of fanfictions, the development often focuses on the emotional aspect too. Inuyasha, as a child, might be more vulnerable and show a side of himself that he usually hides. His relationship with Kagome could become more like a big - sister - little - brother dynamic at first. And as the story progresses, they might face new challenges together, with his enemies seeing this as an opportunity to strike, while his friends are determined to protect him and find a cure for his transformation.
In fanfictions where this happens, the development can vary widely. One common way is that Naruto's transformation into the Kyuubi causes a rift in the ninja world. Some villages might see it as an opportunity to attack Konoha while it's dealing with this internal crisis. Meanwhile, Naruto himself is trying to regain his humanity. His friends, especially those closest to him like Kakashi and Iruka, would be determined to help him. They might have to face their own fears and prejudices towards the Kyuubi as they try to reach Naruto. There could also be a sub - plot where other jinchuriki are involved, either to help or hinder Naruto's situation.
Often, it starts with the shooting incident. Then, it may show the immediate aftermath, like Anakin being rushed to medical help or his comrades trying to protect him from further harm.
Inuyasha is devastated when Kagome gets hurt. He blames himself, especially if he was supposed to be protecting her. He'll pick her up gently and try to find a safe place to tend to her wounds. He might also call for help from his friends like Miroku or Sango. He'll stay by her side until she recovers, constantly on guard against any further threats.
In some cases, there could be a new love interest for Percy. Maybe a character who was always in the background but now steps forward to comfort Percy. This new relationship might be rocky at first as Percy is still hung up on Annabeth, but over time it could develop into something more serious.
The story could progress with Deadpool having to adapt to his new child form. He might start going to school in the fanfiction world. There, he could get into trouble for his unruly behavior that comes from his adult - like mindset in a child's body. Or he could make new friends who are actually kids and learn about the simple joys of childhood like building sandcastles or playing hopscotch.
Perhaps the cause of Kagome becoming a child in the fanfiction could be a cursed spell from a powerful demon. This demon might have wanted to weaken Kagome's powers as she was a threat. As a child, Kagome could have some child - like innocence and different abilities. For example, she might be able to communicate with certain spirits more easily because children are often seen as more pure in such fictional settings.
Mentally, his ninja skills could be both a help and a hindrance. On one hand, he has the knowledge of all the advanced techniques he learned as an adult. But on the other hand, his child - sized body might not be able to handle the chakra flow required for those techniques. His stealth skills might also change. As a child, he could potentially be more inconspicuous in some situations, but at the same time, he might lack the experience in using his smaller size to his advantage in a real combat situation.
Often, the betrayal is sudden. For example, if it's his friends who betray him, it might start with a small incident that Harry doesn't think much of at first. But then it snowballs into a full - blown situation where his friends turn their backs on him completely. Then Harry has to struggle to deal with this new situation while also facing other threats in the wizarding world.
The story might then focus on Hermione's side of things. She could feel guilty about rejecting Harry and try to be a better friend to him. Or, she might try to set Harry up with someone else she thinks would be a good match for him. Meanwhile, Harry could start to develop feelings for another character as he tries to move on from Hermione's rejection.
Well, it might start with Sirius yelling at Ron and Ron feeling really bad about it. Then, Ron might try to make amends by doing something brave or helpful. For example, he could volunteer for a dangerous mission to prove his worth and show Sirius that he can be trusted.