In this fanfiction, it could be that Draco and Severus leave Harry due to a misunderstanding. They might think that Harry has betrayed them or is no longer on their side. So they decide to leave and form their own group or alliance. This could create a lot of tension and drama as Harry tries to clear up the misunderstanding and bring them back.
Perhaps in the fanfiction, Draco and Severus leave Harry because they are forced to by some external dark force. This could lead to Harry having to face new challenges alone, while Draco and Severus struggle against this force in their own way. They could end up being spies or trying to find a way to defeat the dark power from afar.
One possible reason could be a shift in their loyalties. Maybe they discover some dark secrets about Harry or the side he represents that make them uncomfortable. For example, if they find out that Harry has some hidden motives that go against their own beliefs or values.
The impact would be huge. Harry has always had this complex relationship with Draco and Severus. With them leaving, he might feel a sense of loss but also a new determination. For Draco and Severus, leaving Harry could be the start of a new chapter in their lives. They could end up in different parts of the wizarding world, encountering new people and situations. This could bring about a change in their personalities, and when they eventually cross paths with Harry again, they might be completely different characters.
One idea could be a story where Harry, Draco, and Severus are forced to work together on a dangerous mission to save Hogwarts from a new dark threat. They start off distrusting each other but gradually learn to respect and rely on one another.
In some fanfictions, Draco and Severus might be portrayed as hurting Harry for various reasons. It could be due to the long - standing rivalry between Draco and Harry, with Draco's family's pure - blood ideology fueling his actions. Severus, on the other hand, has a complex relationship with Harry. His actions that seem to 'hurt' Harry could be misinterpreted. For example, his strictness in Potions class might be seen as a form of harm, but it could also be his way of trying to protect Harry in a convoluted way.
Maybe Draco discovers that Severus is being framed for a crime he didn't commit. He then approaches Hermione for help as she is known for her intelligence and problem - solving skills. Together, they start to gather evidence to clear Severus's name and also protect him from those who want to harm him.
It could involve Harry having some sort of dark power or being under a dark influence that leads him to enslave them. Maybe he discovers a long - forgotten spell or artifact that gives him this power.
I'm not a big fan of this sort of fanfiction concept as it goes against the original relationships in the Harry Potter series. However, in the vast world of fanfiction, there might be such works out there. You can try searching on popular fanfiction websites like Archive of Our Own (AO3) or Fanfiction.net.
They might hurt Harry physically in some fanfictions. For example, in a fight scene where Draco uses dark magic he's not supposed to and Severus doesn't stop him in time. Another way could be emotionally. Draco could spread false rumors about Harry, which Severus, as a teacher, fails to address properly, leading to Harry's isolation and emotional distress.
In some of these fanfictions, an interesting plot development could be Severus having to deal with the boys' different personalities. Harry, being brave and impulsive, while Draco is more reserved and proud. Severus has to find a way to balance their needs. For example, when it comes to their magical education, he might have to teach them in different ways. He could also have to handle the outside world's reaction to him adopting both a former 'enemy' (Harry) and a pure - blood Slytherin (Draco). Another aspect could be how the boys form a bond with each other through Severus' influence. They might start to see past their initial differences and become like brothers, which changes the whole dynamic of the wizarding world they live in.
One possible plot could be Severus saving baby Draco from a dangerous situation. Maybe there's a dark wizard targeting the Malfoy family and Severus steps in to protect Draco. This could start a special connection between them.