In some fanfictions, Draco's expulsion might be due to a new, strict headmaster who has zero tolerance for the Malfoy family's traditional antics. This forces Draco to re - evaluate his life and values, and he may end up becoming a better person as a result of this expulsion.
You can start by looking on fanfiction - specific websites like FanFiction.net or Archive of Our Own (AO3). These platforms have a large collection of Harry Potter fanfictions, and you can use the search function to specifically look for stories about Draco being expelled from Hogwarts.
One great 'Expelled Draco Hermione' fanfiction is 'The Unforeseen Bond'. It delves into a world where Draco and Hermione are both expelled for reasons that are initially mysterious. The story beautifully weaves their relationship as they struggle together against the unfairness of their expulsion and discover hidden aspects of the wizarding world. Another one is 'Expelled into a New Reality' which has a unique take where their expulsion leads them to a parallel magical realm where they must rely on each other to survive and in the process, their feelings for each other start to change.
One common theme is redemption. Draco often has to redeem himself from his past actions as a Slytherin. For example, if he tries to help Hermione who has been expelled or is at risk of being arrested. Another theme is forbidden love. Their houses and past enmity make their relationship something that is not easily accepted in the wizarding world.
Well, it could be a fanfiction where Draco is jailed in the Hogwarts setting. Maybe he's been caught doing something bad, like getting involved in dark magic activities or plotting against other students. But without reading it, it's hard to say for sure.
In Hogwarts fanfiction, Draco could potentially crawl through secret passages. There are many hidden corridors and tunnels in Hogwarts, and Draco might be exploring them in a sneaky way, perhaps on a secret mission or just to find a quiet place away from others.
A dark wizard or witch from outside Hogwarts could be the main antagonist. They might target Harry specifically because of his reputation as the 'Chosen One' and use their influence to get him expelled from Hogwarts so that he is more vulnerable and easier to attack.
Perhaps Harry accidentally unleashes a powerful and uncontrollable magic spell within the school grounds that causes a great deal of damage. Despite it being an accident, the Hogwarts administration, fearing further chaos, decides to expel him. Harry would then have to go on a journey to learn more about this magic and how to control it, all while trying to prove to Hogwarts that he is worthy of being readmitted.
In some fanfictions, Harry might be expelled for being wrongly accused of using dark magic. Maybe someone framed him by planting dark magic items in his dorm. Another reason could be that he continuously breaks school rules in a way that the school can't tolerate, like sneaking into the Forbidden Forest too many times without permission.
It could make Draco feel exposed and vulnerable at first. But if Hogwarts uses the knowledge from his memories to help him, Draco might develop a newfound respect and loyalty towards Hogwarts. He could see it as an entity that truly cares about him rather than just a place of learning.