How about Gollum from Lord of the Rings? It seems really odd at first, but think about it. Gollum's sneaky nature and knowledge of dark places could be useful in Arkham Asylum. Batman could try to control Gollum's greed and use his skills to navigate the more dangerous parts of the asylum. And Gollum might be fascinated by Batman's shiny gadgets. It would be a very strange and interesting dynamic.
One idea could be that the Winchester brothers from Supernatural are investigating a series of strange murders in Gotham City. They cross paths with Batman who initially is suspicious of them. Eventually, they realize that a demon is behind the killings and they team up. Batman provides his detective skills and combat abilities while the Winchesters use their knowledge of the supernatural to defeat the demon.
Another one worth checking out is 'The Caped Crusader in RWBY'. It delves deep into how Batman's code of ethics might change or stay the same in the RWBY universe. It also has some great fight scenes where Batman uses his martial arts skills against Grimm, all while trying to understand the complex politics of Remnant.
One great Batman crossover fanfiction is 'Batman and the Avengers: A Dark Alliance'. It combines the gritty world of Batman with the super - powered heroes of the Avengers in an exciting way. The story has some great action scenes and interesting character interactions, like Batman's tactical mind clashing with Iron Man's high - tech approach.
One of the best elements is seeing Batman interact with characters from different universes. For example, when he teams up with Superman, we get to see how their different moral compasses and powers play off each other. Another element is the new villains or threats that are created by the crossovers. It adds a fresh perspective to Batman's world.
Another possibility is a scenario where Voldemort decides to expand his reach into the non - magical world and Batman becomes aware of this threat. He would then enter Hogwarts undercover to learn about magic and form an alliance with the Order of the Phoenix. The contrast between Batman's brooding, non - magical detective nature and the magical world would make for an interesting story.
Arrow is a hero who has grown from a playboy to a more serious protector of Star City. He has a sense of humor that is a bit darker and more sarcastic. Batman, while also having a dark side, is more stoic. Their different personalities could create some humorous moments in a crossover. For instance, Arrow might make a sarcastic comment about Batman's overly - serious approach, which could break the tension in a difficult situation. And while they might seem at odds initially because of their different ways of handling things, they would eventually realize that their combined efforts, with their unique personalities, are what will be needed to save the day.
The Reverse - Flash would be really interesting. He could target both Batman and the Flash. For the Flash, he's a long - time nemesis, but for Batman, he'd be a new and extremely dangerous threat. His ability to manipulate the speed force and time could put Gotham in chaos in ways Batman has never seen before. And he could use his knowledge of the Flash to try and set traps for both heroes.
One common theme is the clash of different Arkham versions of characters. For example, when different interpretations of the Joker from various Arkham games meet. It creates interesting dynamics and often leads to intense showdowns.
One common theme is the contrast between their powers and personalities. Superman is all - powerful and has a more optimistic view, while Batman is a normal human with great skills and a darker, more brooding nature. Their interactions based on these differences are often explored.