Maybe Scarecrow. He could be using Arkham Asylum as a testing ground for his new and more potent fear toxins. Harry would be directly affected by these toxins, and he has to overcome his fears while also trying to stop Scarecrow from spreading the toxins further among the inmates and staff.
The Joker could be the main villain. He might see Harry as a new plaything and constantly torment him with his cruel pranks and mind games, making Harry's stay in Arkham a living nightmare.
He could meet the Joker. The Joker is a well - known character in Arkham Asylum, and his chaotic nature would surely create an interesting interaction with Harry.
One possible plot could be Harry exploring the dark secrets of Arkham Asylum. He might encounter various infamous inmates and try to survive their threats while also uncovering a conspiracy within the asylum's walls.
In this fanfic, Harry could be sent to Arkham Asylum for some mysterious reason. Once there, he might discover secrets about the asylum that the authorities are trying to hide. He could start to question his own sanity as he witnesses the extreme cases of mental illness around him. And perhaps, through his experiences, he might find a way to bring some sort of change or hope to that desolate place.
He could interact with the Joker. The Joker might play mind games with Percy, trying to drive him to the brink of madness. Also, Harley Quinn could be there, perhaps befriending Percy in a strange way or using him for her own devious plans.
The plot could involve Percy arriving at Arkham Asylum, perhaps as a new patient or a visitor. He might encounter various iconic villains from the Arkham universe and have to navigate the dangerous and chaotic environment. Maybe he has a special ability or knowledge that makes him stand out among the inmates and staff.
The main characters include Batman, who is on a mission to bring order to Arkham Asylum. Then there's the Joker, whose crazy antics and evil plans are central to the story. Harley Quinn is also a significant character as she is often involved with the Joker's schemes. And characters like Scarecrow, who uses fear as his weapon, also play important roles in the overall narrative of Arkham Asylum City Story.
Batman is one of the main characters. He is constantly trying to keep the inmates in check and solve the mysteries within Arkham. The Joker is also a prominent character, with his chaotic and unpredictable nature adding to the dark allure of the stories.
The Joker could be a main antagonist. Given his history with Jason Todd, he might try to further torment him in Arkham. He could play mind games with Jason, trying to break his already fragile mental state.
In such a fanfiction, Harry Potter could bring a new perspective to Arkham Asylum. He has faced dark wizards and dark magic, so he might see similarities in the deranged minds of the asylum's inmates. His Gryffindor courage would lead him to explore the place, perhaps making unexpected alliances with some of the more misunderstood inmates, all while trying to keep his magical identity a secret to avoid chaos.
In addition to the main ones, there could be other inmates like Scarecrow. His fear - inducing tactics can create some really intense scenes when interacting with Batgirl. Poison Ivy might also be present, especially if the story involves some sort of ecological or plant - related mystery within Arkham. And then there are the guards of Arkham Asylum, who can be either helpful or obstructive to Batgirl's goals.