One possible scenario could be that Harry grows up on the streets, learning to fend for himself and developing a tough exterior. He might encounter some kind of mentor figure who helps him discover his magical abilities in a very different way than in the original story.
One common plot twist is that his family actually has a noble reason for abandoning him. Maybe they were trying to protect him from a greater evil that they knew was coming for him. Another is that Harry discovers he has a hidden power that his family was afraid of, which led to the abandonment. For example, he could have a power that is considered dark but is actually something that can be used for good.
Snape could also be a central figure. Maybe he discovers Harry's situation early on and has a change of heart. He could secretly guide Harry, teaching him things about magic and the wizarding world that he otherwise wouldn't know, all while still maintaining his aloof exterior.
One possible plot could be Naruto growing up alone and having to fend for himself. He might develop a very independent and distrustful nature towards others at first. Maybe he starts to question his self - worth, but then through his own determination and some unexpected friendships, he begins to rise above his difficult past and prove himself to the village in ways no one expected.
He would probably try to figure out what went wrong. Harry is a curious and determined character. He might start to recall recent events to see if there were any signs of his friends' discontent. He could also try to reach out to them, either directly or through mutual acquaintances, to ask for an explanation.
In such fanfictions, Harry might overcome the emotional trauma by finding true friends. These friends could provide the love and support his family didn't. For example, he could meet someone like Hermione who is intelligent and empathetic. She could help him study and also be there for him emotionally. Another way is through self - discovery. Harry could realize his own worth outside of his family's view of him. He might discover he has unique magical abilities that make him special and valued in the wizarding world.
One possible reason could be jealousy. Maybe Harry has achieved something great and his friends can't handle his success. For example, if he gets a very important role in a magical competition, his friends might feel overshadowed. Another reason could be a misunderstanding. Harry might be wrongly accused of something, like being in league with the dark side, and his friends, in their fear or haste, abandon him without giving him a chance to explain.
It could be a relative from his family who was behind the abandonment. Maybe they want to keep Naruto away from some family secret or power, and they will do anything to stop him from finding out the truth.
Maybe it's Ron. Suppose Ron gets jealous of Harry's fame and power and, in a moment of weakness and envy, decides to abandon Harry to die. This would create a lot of drama as Ron and Harry have been friends for a long time, and such a betrayal would be a huge shock to the story's readers.
One possible plot could be that Harry's mate is influenced by dark forces. Maybe they are threatened or corrupted, which leads them to abandon Harry. Harry then has to find his own way to survive. He might discover new powers or allies in the process, and in the end, seek revenge on those who made his mate turn against him.