One idea could be exploring what would happen if a hero from the Marvel universe was wrongly accused of a crime in the Injustice world. For example, Spider - Man being framed for a mass destruction event. Another could be a story about how the X - Men would deal with the unjust laws in the Injustice setting. Maybe they would form an alliance with some of the Injustice heroes to fight for mutant rights within that corrupted system.
You could create a fanfiction around Black Panther. He comes from a highly advanced and just society in Wakanda. So, in the Injustice world, he could try to introduce some of Wakanda's principles to reform the broken justice system. He might face opposition from the tyrannical forces in that world, but his skills, intelligence and the resources of Wakanda could make for an exciting story.
One idea could be exploring an alternate ending where the heroes and villains form an uneasy truce much earlier. This would change the power dynamics in the Injustice universe significantly. Another idea is to focus on a minor character's perspective during the major events, like a civilian caught in the crossfire.
How about a crossover with the 'Watchmen' universe? The complex and morally - gray characters from 'Watchmen' would fit well into the 'Injustice' world. Rorschach's unwavering sense of justice, no matter how extreme, could either clash or find common ground with the characters in 'Injustice'. It would be a great exploration of different concepts of right and wrong in a superhero - filled world.
An interesting Injustice OC fanfiction could center around an OC who is a time - traveler. This character could go back in time to try and prevent the events that led to the Injustice storyline. They would face challenges like not changing too much of the timeline while still trying to stop the chaos.
One idea could be the Avengers facing off against a new, unjust system within their own superhero community. Maybe some heroes are being wrongly persecuted due to false accusations of using their powers for personal gain. This would create a lot of internal conflict as they try to clear their names and fight against the system.
One idea could be exploring Batman's internal struggle in the Injustice universe more deeply. Maybe he has a nightmare where he becomes like the tyrannical Superman, and this makes him question his own actions and methods even more.
A story about an OC who is a healer in the Injustice 2 world could be really engaging. In a world full of battles and destruction, this OC could be trying to heal not only the physical wounds but also the emotional and psychological damage that the characters have endured. They might face challenges like being kidnapped by villains who want to use their healing powers for their own evil purposes.
One idea could be that Batman tries to train Supergirl to better control her powers in the context of the Injustice 2 universe. He might see her as a potential force for good against the tyrannical regime. Another could be that Supergirl discovers a way to bring back the more heroic Superman she once knew, and Batman has to decide whether to trust her plan or not.
One idea could be exploring an alternate universe where Terry McGinnis (Batman Beyond) is pulled into the Injustice universe and has to deal with the morally compromised heroes. He might try to find a way to bring back the true sense of justice among them. For example, he could start by trying to reason with Superman, showing him the error of his ways through his own experiences in his own universe.
One idea could be exploring how the Young Justice team would react to the dystopian world of Injustice. For example, they might try to find a way to restore justice and balance without using the extreme methods seen in the Injustice universe. Maybe they would focus on rehabilitating the villains instead of just punishing them.
A cool 'injustice crossover fanfic' could involve 'Injustice' and the 'Watchmen' universe. The gritty and morally complex world of 'Injustice' would contrast well with the unique and dark 'Watchmen' universe. Rorschach could find himself in the 'Injustice' universe and his uncompromising view of justice might clash with some of the characters there, while Dr. Manhattan's god - like powers could be a major factor in the story, either as a threat or an unexpected ally.