A great plot could involve a race against time. A powerful new super - weapon is about to be unleashed in Gotham and New York simultaneously. Spiderman and Batman have to put aside their differences and work together to stop it. Along the way, they learn from each other's fighting styles and detective skills.
One idea could be that Batman suspects Superwoman of being controlled by some unknown force. So, he starts to investigate her in secret. Superwoman, on the other hand, notices Batman's strange behavior and thinks he's up to no good. This leads to a series of confrontations between them.
In a fanfiction, perhaps a powerful tech mogul has created a dangerous new form of artificial intelligence that threatens both Detroit (Robocop's city) and Gotham. Robocop and Batman cross paths while investigating the same lead. Robocop is intrigued by Batman's ability to operate without the high - tech enhancements he has. Batman, on the other hand, is interested in Robocop's in - built weaponry and combat capabilities. They combine their resources and fight the AI - controlled robots and henchmen.
One idea could be that Robin discovers a dark secret about Batman's past that makes him question their relationship, leading to a tense confrontation. For example, if Robin finds out that Batman once made a deal with a villain that had far - reaching consequences. Another plot could involve a new villain manipulating Robin into believing Batman is a threat to Gotham, causing them to fight. Maybe the villain uses mind - control technology.
A possible plot in Poison Ivy vs Batman fanfiction is that Poison Ivy creates a massive garden in the middle of Gotham that starts to overtake the city. Batman is torn between respecting her love for nature and protecting the city. He tries to negotiate with her, but she refuses to budge. This leads to a series of battles and chases as Batman tries to find a way to either relocate the garden or find a compromise. Another idea could be that Poison Ivy discovers Batman's secret identity and uses it to blackmail him into helping her with her environmental goals, which Batman resists, creating a tense stand - off between them.
One idea could be that Batman and Superman are forced to team up against a common enemy from another dimension. This enemy has the power to manipulate the minds of the citizens of Metropolis and Gotham, making them turn on their heroes. Batman uses his detective skills to find the source of the mind control, while Superman has to hold off the hordes of brainwashed civilians.
A possible plot idea is that Batman discovers a dark secret within the Justice League that they are unaware of. This secret could be something that could potentially destroy the League or change their moral compass. Batman then has to decide whether to confront the League directly or try to fix the problem on his own, which causes the 'vs' situation as the League may see his actions as a threat.
One idea could be an OC who has the power to nullify Superman's powers temporarily, making the fight more evenly matched against Batman. This OC could be a scientist who has developed a special device after years of studying Kryptonian physiology.
One interesting plot could be Batman's distrust of the Justice League's unrestrained power leading to a full - on confrontation. He might secretly plan to take down each member one by one, using his intellect and prep time. Another could be the Justice League being mind - controlled and Batman having to fight them to break the control.
Another idea could be a team - up against a greater threat. Despite their differences, they realize that a powerful enemy is beyond their individual capabilities. They have to combine their skills, Batman's detective skills and high - tech gadgets with Rorschach's street - smart and unorthodox fighting style. This could lead to some great action scenes and also character development as they learn to work together.
One idea could be a misunderstanding. Maybe a villain manipulates information to make Batman think Nightwing has turned bad. So, Batman starts to hunt Nightwing, while Nightwing is confused and has to prove his innocence.