In some versions of 'harry becomes an obscurus fanfic', the key plot could be Harry's journey to master the Obscurus power. He might start out as an outcast because of it, but then discovers that it can be a weapon against the real threats in the wizarding world. His relationship with Dumbledore or other authority figures might change as they try to help or restrain him. And there could be a big showdown where he has to decide whether to fully embrace or reject the Obscurus within.
The main character is Harry, of course. But in addition to Ron and Hermione, other characters could be significant. For example, Voldemort or his followers might sense Harry's new power and become interested in using it for their own evil purposes. So they could be antagonists in the fanfic. Also, some new characters might be introduced, perhaps a wizard or witch who has some special knowledge about the Obscurus and tries to guide Harry on his journey, either for good or bad motives.
In a Naruto becomes a Kitsune fanfic, a major plot point could be Naruto's training to master his Kitsune powers. Since Kitsune are often associated with illusions and trickery, he might have to learn to use these abilities without getting lost in them himself. He could also face enemies who are either after his Kitsune powers or are themselves Kitsune with different motives. This would lead to some intense battles and power struggles. And of course, his journey to understand the Kitsune heritage and how it fits into his own identity as a ninja would be a central plot element.
In a 'harry saves everyone fanfic', one key plot point could be Harry discovering a new, hidden power within himself. This power might be the key to saving everyone. He could also form new alliances with unlikely characters. For example, he might team up with some Slytherins who have a change of heart. Another aspect could be that the situation is extremely dire, like the whole wizarding world is on the verge of destruction. Harry then has to go on a quest to find ancient magic or artifacts that can turn the tide and save all the wizards and witches from harm.
One key plot point could be Sakura's training. She might start from being a novice, learning various assassin skills like stealth, combat, and weapon handling. Another point could be her first mission. It could be a dangerous one where she has to prove herself. Also, her relationships with other characters in the assassin world, whether they are mentors, rivals or allies, would be important in shaping the story.
One interesting 'obscurus harry potter fanfic' could be about Harry learning to control an obscurus within him in a way that the original books didn't explore. Maybe he discovers ancient magic that helps him tame it and use it for good, like protecting Hogwarts from a new dark threat.
In this fanfiction about Issei becoming a dragon god, a main plot point would likely be the origin of his transformation. It could be a prophecy or a hidden power within him that gets awakened. As he becomes a dragon god, he would have to face new challenges. For example, there could be ancient enemies of the dragon gods that come after him. His character development would be crucial. He would need to grow from a regular person (in the context of the story) to a being with great power and wisdom, and this journey would be filled with various trials and tribulations.
The plot might start with Snape realizing that Harry is in need of a proper family. So he decides to adopt him. As the story progresses, they would need to adjust to living together. Snape would have to change his living quarters to accommodate Harry. There could be a lot of emotional moments like when Snape tells Harry stories about his mother. Also, the fanfic could explore how Snape helps Harry deal with his fame in a different way than the Dursleys did. He could teach Harry to be more humble and use his fame for good in the wizarding community.
One key plot point could be the moment when Snape first shows a sign of not hating Harry. Maybe it's during a dangerous situation where Snape protects Harry instead of being cold towards him.
I'm not sure specifically as there could be many different takes in such a fanfiction. It might explore Harry's journey if he was an Obscurus, perhaps dealing with the dark and uncontrollable magic within him and how it affects his relationships and his role in the wizarding world.
One possible plot point is how Deku as a girl interacts with female characters. She could form new friendships or rivalries with them. For instance, she might bond more closely with Uraraka now that they share the same gender. And in terms of her hero training, she may face different challenges and opportunities compared to when she was male.