In the fanfiction, it could be related to family values. Draco comes from a family with certain beliefs about blood purity. Hermione being a Muggle - born might be seen as beneath him by his family's standards. So, Draco might abuse Hermione as a way to show his superiority based on those wrong family - instilled ideas.
It could also be due to peer pressure. Draco might be trying to impress his Slytherin friends or live up to the so - called 'Slytherin image'. His friends might encourage or at least not discourage his behavior towards Hermione, and he goes along with it, resulting in the abuse.
One possible reason could be that Draco has had a change of heart. Maybe he realizes that Hermione is a person worthy of protection regardless of her House or her friendship with Ron. He might have seen some injustice about to befall her from Ron and his Gryffindor bravado getting out of hand.
There could be some underlying mental health issues within the family. Perhaps her parents have some undiagnosed conditions that make them more prone to lashing out. In the fanfiction world, this could be explored further, like how Hermione tries to understand and deal with this aspect of her family situation while also dealing with the abuse.
One possible reason could be their different backgrounds and values. Hermione is a Muggle - born witch who values knowledge, justice, and equality. Draco, on the other hand, comes from a pure - blood family with a long - standing tradition of pure - blood supremacy. These fundamental differences might lead to constant clashes in their marriage, causing them to grow apart and eventually divorce.
In some fanfictions, their fight might be due to a competition at Hogwarts. Maybe they are both vying for the top spot in a particular class or for a special award. Hermione's studious and competitive nature combined with Draco's pride and desire to outdo others could easily result in a fight.
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 it's part of a power play. Draco comes from a pure - blood family and Hermione is a Muggle - born. In some fanfictions, this power dynamic is explored more deeply. By cutting her hair, he is trying to assert his superiority over her. It could also be an impulsive act in the heat of an argument. They might be arguing about something like blood purity or house points, and he lashes out in a very physical and mean - spirited way.
Some writers might do it to explore the darker sides of the characters. They want to see how Hermione, who is usually so strong and intelligent, would react in such a terrible situation. And for Draco, it could be a way to show his capacity for evil in a more extreme way than in the original books.
There could be several reasons. Draco might be facing some sort of blackmail. Someone could be forcing him to be with another person for some hidden motives. Also, his own pride could play a part. He may not want to admit that he's falling for Hermione, a Muggle - born in the eyes of some in the wizarding world. So, to prove to himself that he doesn't care about her as much as he thought, he cheats. Additionally, he could be influenced by the peer pressure within the Slytherin house, where some might not approve of his relationship with Hermione and push him towards someone else.
Love. Just like any other character, Draco can be heartbroken in fanfiction. If he loses someone he loves, whether it's a friend or a romantic partner, he could cry. It shows his vulnerability and that he's not just the tough - guy Slytherin he often tries to be.
One possible reason could be his Slytherin pride and the long - standing rivalry between Gryffindor and Slytherin. He might have said something mean to Hermione in the heat of that rivalry. Another reason could be jealousy. Maybe Hermione is achieving more academically or getting more recognition, and Draco, being a proud pure - blood, can't stand it.