Perhaps he was cursed. In the wizarding world, there are many dark curses that could affect a person's mind, and one such curse could target his emotional understanding. Also, it could be due to his isolation. Harry has often been alone or felt alone, and this lack of regular social interaction with a diverse range of people could have made it difficult for him to develop a normal understanding of emotions.
One common theme is isolation. Since Harry has no emotions, he often finds it hard to connect with others, which leads to a sense of isolation. Another theme is self - discovery. As the story progresses, Harry may start to question what it means to be human without emotions and try to understand his own identity in a different way.
One 'harry no emotions fanfiction' that might be interesting is 'The Emotionless Boy Who Lived' on FanFiction.net. It explores a unique take on Harry where his lack of emotions changes his interactions and the overall story arc in unexpected ways.
One possible reason could be to protect himself from the pain and loss he has endured. After all he's been through, like the death of his parents, Sirius, and so many others, turning off his emotions might seem like a way to avoid further hurt.
It could also be related to his self - preservation in the wizarding society. In a world full of magic and danger, showing too much emotion might be seen as a weakness. Harry, being aware of this, decides to shut out his emotions to appear stronger. He has faced a lot of scrutiny and jealousy from some students and even some adults in the wizarding world. By suppressing his emotions, he hopes to be more respected and less of a target.
The romances in the Harry Potter series would be non - existent. The slow - burning love between Ron and Hermione or the unrequited love of Snape for Lily would be completely absent. Instead, interactions would be more matter - of - fact. For instance, if Ron and Hermione were to go to the Yule Ball together, it would be just for the sake of following the social norms of Hogwarts, not because of any budding feelings.
It could be a very different take on the Harry Potter universe. Without emotions, the characters might seem robotic. For example, Harry's fight against Voldemort could be more like a strategic battle without the emotional drive of revenge or protecting his friends. It would be a cold, calculated world where magic is just a tool and not something that is tied to the characters' feelings.
Often, relief is a big emotion. After facing a lot of danger, like in a fight against dark wizards, their hug is a sign that they are okay. It's like a physical way of saying 'we made it through this together'.
In 'Harry Loses His Emotions Fanfiction', it could be that Harry experiences a really traumatic event. Maybe he witnesses the death of a very close friend in a battle. This shock is so great that it makes him shut down his emotions as a self - defense mechanism. He then becomes cold and distant, and the story could be about how his friends struggle to reach the old Harry again and help him heal.