One possible reason could be extreme anger. Maybe Draco has insulted Harry's friends or family in a really cruel way. For example, if he made a very offensive comment about Harry's parents, Harry's emotions could get the best of him and he might almost lose control and come close to killing Draco.
It could be related to a misunderstanding. In the wizarding world, there are often complex plots and misinformation. If Harry believes Draco is involved in something truly evil, like helping the Dark Lord in a major way that endangers many lives, he might be pushed to the brink. For instance, if there are false rumors that Draco has a key role in a new dark plot against Hogwarts.
In the 'harry rejects draco fanfiction', it could be due to the social divide between Gryffindor and Slytherin. Harry, as a Gryffindor, has been taught to distrust Slytherins. Draco's actions towards Harry's friends, like Hermione who is a Muggle - born, also contribute. Harry may reject Draco because he stands for the discrimination that Hermione has faced from Draco and his family.
In fanfiction, their kiss might be a way to break free from the expectations placed on them. Harry is always seen as the hero and Draco as the villain's sidekick. By kissing, they are defying those roles and expectations. It could also be a way to gain power over each other in a different sense. Instead of the usual power struggle based on magic or family name, the kiss becomes a new form of power dynamic between them.
One reason could be to add drama and conflict to the story. Fanfiction writers often like to create complex situations to make the plot more interesting. Another reason might be to explore different aspects of the characters' personalities in a non - traditional way.
Jealousy could be one motive. They might be jealous of Harry's special status as a wizard. They see him as different and a threat to their 'normal' family life, so they want to get rid of him.
One reason could be love. Draco might have fallen deeply in love with Harry and his possessiveness is a way of showing his strong feelings. He doesn't want to lose Harry to anyone else.
A possible reason could be that Harry is feeling the weight of his responsibilities. He has to constantly fight against Voldemort and protect the wizarding world. When Draco sees Harry cry because of this, it shows the toll it's taking on Harry. Another reason might be a personal loss. If Harry loses a friend or a mentor, Draco could witness his grief.
One possible reason could be his family's status in the wizarding world. His family might be involved in some dark deeds, and Draco could be a target because of that. Another reason could be related to his own actions or attitudes that have made him enemies.
Perhaps Draco has developed some sort of complex feelings towards Harry. He could be secretly attracted to Harry and treating him like a baby is a way to get closer to him without admitting his true feelings. Or it could be that Draco has changed as a person and now views Harry as someone who needs his support and guidance, just like one would for a baby.
Maybe Draco says some really mean and hurtful words to Harry. For example, he might make fun of Harry's family situation, like his parents' death or his relationship with the Dursleys. Words like that can be really cutting and could easily make Harry cry.
One possible reason could be a misunderstanding. Maybe Harry misinterprets Draco's actions or words in a way that makes him do something that breaks Draco's heart. For example, if Draco is secretly trying to help Harry but Harry thinks he has some malicious intent and publicly shames him.