It could also be that Hermione, after being abandoned, decides to leave Hogwarts for a while. She travels to different magical places, perhaps some ancient wizarding libraries or hidden magical communities. There, she meets Draco Malfoy who is also on some sort of self - discovery journey. At first, they are both hesitant around each other, but as they share their experiences and knowledge, they start to form a bond.
Hermione may also become more empathetic towards those who are considered outsiders, like Draco. Having been abandoned by her closest friends, she can understand what it's like to be alone. This could lead to her reaching out to Draco in a way she might not have before. She could see past his Slytherin exterior and try to understand his insecurities and motives, which in turn could change her own character as she becomes more open - minded.
It could be that Ron and Hermione abandon Harry due to a prophecy that they misinterpret. They believe that by being with Harry, they will bring doom to the wizarding world. So they go into hiding. Harry, on the other hand, is determined to change the course of the prophecy. He embarks on a journey to find the truth behind it, all while feeling the pain of his friends' desertion. He has to fight against dark forces that are taking advantage of the situation.
In such a fanfiction, it might be that Harry and Ron are influenced by a powerful dark spell. This spell makes them see Hermione as a threat, so they abandon her. Hermione then has to find a way to break the spell's influence on them while also dealing with the loneliness and danger she's now in. She could seek help from other Hogwarts students or even some friendly magical creatures.
Hermione would probably be deeply hurt at first. She trusts Harry and Ron so much, and being abandoned by them would be a huge blow. But she's also very determined. So, she might throw herself into her studies even more, using her knowledge as a way to cope and also to find a solution to the situation.
At first, Harry could be heartbroken. He would wonder what he did wrong to make them leave. He might try to find them and reason with them. However, if he can't reach them, he would likely turn that pain into a driving force. He would focus on his goals, like fighting against Voldemort or protecting the wizarding world, even more fiercely, because he now has to prove himself not only to the world but also to his former friends.
One possible plot development could be that Hermione is left with a deep sense of guilt and responsibility. She might then take on Harry's mission or cause in his memory. For example, if they were fighting against a new dark wizard, Hermione could become even more determined to defeat the enemy.
One possible plot development could be that Dark Harry has some ulterior motive for kidnapping Hermione. Maybe he wants to use her knowledge to further his dark plans. For example, Hermione is known for her intelligence and vast knowledge of magic, and Dark Harry might force her to help him find a powerful and dark magical artifact.
A well-known Dramione fanfiction with this plot is 'Love's Betrayal'. Here, Ron's cheating triggers a series of unexpected events that bring Draco and Hermione closer together.
One possible plot development is that Ron gets angry at first. He might suspect Draco of doing something malicious on purpose. But as he investigates, he realizes it was an accident. Then he works with Draco reluctantly to break the spell on Hermione.
Hermione might seek revenge. Given her intelligence and magical abilities, she could use her skills to get back at Harry and Ron for their betrayal. This could lead to a big rift in their friendship and even endanger their common goals in the wizarding world. She might also side with other characters who are against Harry and Ron, changing the whole dynamic of the story.