It could be a corrupt politician in the real world who somehow discovers Takemi's connection to Joker and tries to use her to get to him. This politician might be involved in some illegal activities that Joker is trying to expose, and he sees Takemi as a way to stop Joker.
A possible plot could be a story where Takemi is kidnapped by an enemy in the Metaverse. Joker, of course, goes on a mission to rescue her. Along the way, he discovers that Takemi has some hidden strengths that she has never shown before. After the rescue, their relationship changes from just acquaintance to a more intimate friendship or even something more as they realize how much they mean to each other.
In Harley Quinn x Joker fanfic, the character development is often a focus. Harley's transformation from a psychiatrist to a criminal sidekick is interesting. Writers may play with different timelines and scenarios in the fanfic. For example, they might explore what would happen if Harley finally broke free from the Joker's influence earlier than in the original story. This can lead to various plot twists and new character arcs for both Harley and the Joker.
The themes in 'joker x harley fanfic' often include the blurred lines between sanity and madness. Both characters are on the edge of sanity, and their relationship is affected by this. Dependency is also a big theme. Harley depends on Joker, and the fics explore how she can become independent. And finally, there's the theme of transformation. Harley might transform from a submissive character to a more assertive one in the relationship.
One popular trope is the 'redemption arc' for the Joker. In some fanfics, there's an attempt to show a softer side of him, perhaps because of Harley's influence. This can be controversial as it goes against the traditional view of the Joker as pure evil.
Writing such sexually explicit fanfic is inappropriate. It violates ethical and moral standards, especially when it involves sexualizing characters from a game or other media. This kind of content can also make many people uncomfortable and goes against the positive and healthy image that the original work may be trying to convey.
One common theme is the battle of ideologies. Bruce Wayne stands for a world of rules and order, while the Joker wants to disrupt it all. Another theme could be redemption, where either character might be on a path to change. Also, the theme of obsession is often present, as the Joker is obsessed with Batman and vice versa.
In 'Bruce Wayne x The Joker Fanfic', their relationship is often complex. It's a clash of two extreme personalities. Bruce Wayne, as Batman, represents order and justice, while the Joker is chaos incarnate. Their interactions can range from intense battles to psychological mind - games. This relationship is what makes many fanfics so interesting as it explores the duality of good and evil in a unique way.
Another theme is often the self - insert character getting involved in the Joker's world of crime and chaos. They might be trying to change him or just survive in that wild environment. It's about how an ordinary person (the self - insert) would interact with such an extreme character like the Joker. And there could also be themes of self - discovery as the self - insert character is thrust into this unusual situation with the Joker.
A good 'Joker x Harley Quinn fanfic' should have a deep understanding of their characters. It needs to capture the Joker's insanity and Harley's devotion. For example, it could show how Harley is both attracted to and repelled by the Joker's madness. Also, a strong plot that involves their criminal activities or their relationship drama is important.