Another reason might be related to the political situation in the wizarding world in this fanfiction. If there are new laws or a more authoritarian regime, Harry's actions that were once heroic could now be seen as criminal. For example, his opposition to the Ministry of Magic in the original series could be turned into actual illegal activities in this new narrative.
One possible reason could be a different interpretation of his actions. Maybe in this fanfiction, his use of magic outside of Hogwarts' approved ways is seen more harshly. For example, when he used the Patronus charm to save himself and Dudley in the 'Order of the Phoenix', in this alternate view, it might be considered a criminal act due to the Statute of Secrecy implications.
It could be that the author wants to explore a darker side of Harry's character. Perhaps they see his natural inclination to break rules, which was often for good in the original series, as something that could lead him down a more criminal path. For instance, his sneaking around in Hogwarts at night could be construed as more devious behavior rather than adventurous in this fanfiction.
One reason could be a reaction to the Ministry of Magic's mismanagement. In the original story, the Ministry often made mistakes and had corrupt elements. In fanfiction, this could lead to Harry becoming an anarchist as a way to oppose such a flawed system.
It could be due to a spell. There are many dark spells in the wizarding world that might cause a person to feel cold. For example, some curses can drain the warmth from a body. If Harry was targeted by such a spell, he would be cold. Also, it might be related to his emotional state. If he was feeling lonely or scared, it could make him feel cold inside, just like when people are in a bad mood in real life, they might feel colder than usual.
It could be a case of misinformation. Someone in the story might have spread false rumors about Harry being the father for their own motives. Perhaps they wanted to cause chaos or gain something from the situation. So, the whole idea of Harry being the father is just a false story that gets spread around the wizarding community.
The 'Harry Potter' series is far from being a 'criminal fanfiction'. J.K. Rowling created a magical universe filled with positive values. Harry and his friends are constantly fighting against the real criminals in the story, like Voldemort and his Death Eaters. It's a story about good triumphing over evil, not about criminality.
One reason could be to add more depth to his character. Schizophrenia can bring out complex emotions and behaviors, making Harry more relatable in some ways.
One reason could be jealousy. Harry is famous in the wizarding world, and some students might be envious of that. So they bully him to make themselves feel better.
In fanfiction, Harry Potter might be angry if his friends are in danger and no one seems to be taking it seriously. He's very protective of his friends, like Ron and Hermione. So if some authority figures in the story are being dismissive of the threats his friends face, that would surely make him angry.
One possible reason could be that he's worried about Ginny's safety during the pregnancy. He might be overprotective and his concern comes out as anger.
One reason could be that Harry wants to preserve the integrity of his real story. Fanfiction often takes the original story in different and sometimes wild directions. He might worry that it could distort the truth about his adventures, his friends, and the sacrifices made. For example, some fanfictions might create romantic relationships that didn't exist or change the motives of characters, which could mislead those who are new to the real story of Hogwarts and his battles against Voldemort.
One possible reason could be that he was injured during a battle with dark wizards. Maybe he was hit by a powerful curse that affected his legs. Another reason might be related to some kind of potion gone wrong. For example, if he accidentally drank a potion that had negative side effects on his motor functions.