Maybe a plot where the Riddler manages to escape Arkham during the chaos of the 'Assault on Arkham' and sets up a city - wide riddle - based trap for Batman and the other heroes. The fanfiction could show how each character uses their unique skills to solve the riddles and stop the Riddler. Also, it could explore the relationships between the villains as they are forced to work together to survive the Arkham breakout situation.
A great plot for 'Batman Assault on Arkham Fanfiction' would be if there was a secret society within Arkham that was manipulating the inmates all along. The story could follow Batman as he discovers this society while trying to stop the chaos. It could also involve some of the inmates realizing they are being used and teaming up with Batman, at least temporarily, to take down this secret group. This would add a new layer of mystery and intrigue to the existing 'Assault on Arkham' story.
One idea could be exploring the backstories of the lesser - known characters in the 'Batman Assault on Arkham' universe more deeply. For example, you could focus on Killer Croc's life before Arkham and what led him to become the way he is. Another plot could involve a team - up between unexpected characters from the movie, like Harley Quinn and Deadshot, against a new threat in Arkham that the Bat - family is unaware of.
One idea could be a story where Batman and Catwoman team up to take on a new, more powerful villain in Arkham. Maybe this villain has the ability to control the minds of the inmates, creating chaos. They'd have to use their unique skills, Batman's detective work and combat abilities, and Catwoman's agility and thieving expertise to stop the threat.
One idea could be exploring a new villain in Neo - Gotham. Maybe a tech - based criminal who can hack into the Bat - suit's systems, creating a whole new set of challenges for Terry McGinnis. Another could be a story where Terry has to team up with an old - school Batman villain who has somehow resurfaced in the future, like the Riddler, but with a new high - tech twist on his riddles.
Well, you could write a fanfiction where the Joker somehow returns in Arkham Beyond, but he has a new, more terrifying form. Batman must figure out how this is possible and stop him before he causes even more mayhem. Or perhaps a story centered around Harley Quinn trying to redeem herself in the Arkham Beyond setting. She could team up with Batman to take down a common enemy, which would create an interesting dynamic between the two characters.
You could also do a 'what if' scenario. For instance, what if Batman had to team up with some of the Arkham inmates, like Harley Quinn and Poison Ivy, to stop a greater threat that was endangering not only Gotham but also the inmates' own lives? This would involve exploring their complex personalities and how they might interact with Batman in a different context.
One idea could be exploring how the Knightfall event affects Batman's relationships with his allies in the Arkham Knight universe. Maybe some of them start to question his methods more deeply.
One interesting plot idea could be a fanfiction where the Joker somehow comes back to life in Arkham Knight. Maybe he was only in a coma and wakes up with a new, even more deranged plan to take over Gotham. He could start by manipulating the inmates in Arkham again, creating chaos from within the asylum.
In this fanfiction, it could be interesting if Catwoman discovers a secret about the Arkham Knight that Batman has overlooked. She could use this knowledge to her advantage, either to make a deal with the Arkham Knight or to help Batman. For example, she might find out that the Arkham Knight has a weakness related to a certain location in Gotham that was important to his past. Catwoman could then lead Batman there to take down the Arkham Knight.
One plot could involve Poison Ivy being kidnapped by a new, unknown villain in Arkham. This villain wants to use her powers for their own evil plans. Batman then has to team up with some of Ivy's plant minions (who have a limited form of sentience) to rescue her. During the rescue, we could see a different side of Batman as he tries to understand and communicate with the plant creatures.
One idea could be exploring Scarecrow's backstory in more depth. Maybe show his early days in Arkham Asylum, how he was treated by the staff and inmates, and what led him to become the terrifying Scarecrow. Another plot could involve Scarecrow creating a new and more powerful fear toxin that not only affects Batman but also the citizens of Gotham, and Batman has to race against time to find an antidote while dealing with his own fears.
Killer Frost is alluring in 'Batman: Assault on Arkham' fanfiction because of her powers. Her ability to control ice makes for some really cool (pun intended) action scenes. Writers can use this to create intense battles or escape scenarios. For instance, she could freeze an entire corridor in Arkham to stop guards from chasing her.