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.
Perhaps a fanfiction where Poison Ivy falls ill due to some strange new chemical in Arkham Asylum. Batman, instead of seeing her as just a villain, decides to help her find a cure. This would lead to a journey through the asylum, facing other villains who might want to take advantage of Ivy's weakened state, and also a deeper exploration of Ivy's character and her connection to nature.
A plot idea could be that Poison Ivy creates a new type of plant - based virus in Arkham that only affects humans who are harming the environment. Batman has to find a way to stop the virus from spreading while also dealing with Ivy's strong beliefs. Another idea is that Ivy discovers a rare plant in Arkham that she believes can save the planet, but it's in a highly guarded and dangerous area. Batman and Ivy might have to work together to retrieve it.
A possible fanfiction could focus on a team - up between Poison Ivy and another Arkham character, like Catwoman. They could form an unlikely alliance to take on a common enemy in Arkham City. The story could show their different motives and how they manage to work together despite their differences. For example, Ivy wants to protect the natural environment of Arkham City which is being destroyed by a new construction project, while Catwoman is more interested in the valuable artifacts hidden in the buildings.
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.
Well, a plot could revolve around Poison Ivy being accidentally awakened from a long slumber in the 'Batman Beyond' era. She finds that the world has changed so much that she's almost an alien in it. However, her powers start to mutate in strange ways due to the new environmental factors. Batman Beyond has to figure out how to stop her while also trying to understand what's causing these changes in her. It could also be that she has a connection to a new bio - tech company in Gotham and is using their resources to spread her plants in a more insidious way.
Another plot could be that they have a child who has a unique combination of their powers. This child becomes a target for those who want to use its powers for evil or those who fear its potential. Batman and Poison Ivy then have to protect their family while also dealing with the challenges of being a married couple with very different backgrounds and moral compasses.
A plot could involve Poison Ivy using her powers to create a dream - like state for Batman. In this state, he sees a Gotham where nature and the city co - exist peacefully, which is Ivy's vision. But he also starts to see how he could fit into this world. Meanwhile, outside of the dream, Ivy is protecting Batman from other villains who see his vulnerable state as an opportunity to attack. As he wakes up, he has a new perspective on Ivy and their relationship changes.
Well, a plot might involve Poison Ivy falling in love with Robin in a strange way. She tries to seduce him not just for her own gain but because she actually develops feelings. Batman, of course, sees this as a major threat and tries to separate them. Meanwhile, Poison Ivy's plants start to act out in strange ways due to her mixed emotions. Some plants become protectors of Robin while others are still under her full control and are used to attack Batman. This would create a complex dynamic between the three characters.
One idea could be that Batman tries to resist Poison Ivy's allure in a more comical way. Maybe she uses her powers to make him dance instead of the usual mind - controlling for evil deeds. Another could be that they form an unlikely alliance against a greater threat, and during their time together, there are some humorous misunderstandings because of Poison Ivy's unique personality.
There are fanfictions that explore Poison Ivy's backstory in the Arkham Knight world more deeply. For example, a story might focus on her early days and how she came to have such a strong connection with plants. This can add a lot of depth to her character in the context of the game's lore.