Some Oc and Joker fanfiction focuses on the Oc being a victim of the Joker's madness. The story then follows their journey of either trying to escape or getting revenge. It can be a dark and intense exploration of the Joker's character through the eyes of an Oc.
One interesting Oc and Joker fanfiction could be about an Oc who is a detective trying to outwit the Joker. The Oc has unique skills and a backstory that makes the chase thrilling.
A third idea is that the OC is a mental health professional who gets the chance to treat the Joker in Arkham Asylum. Through their sessions, they learn about his past traumas and how they've shaped him into the monster he is. But the OC also has to be careful not to be manipulated by the Joker, which creates a tense and psychological story.
One idea could be that the OC is a psychologist assigned to study the Joker. As she tries to understand his mind, she gets drawn into his chaotic world. Another could be the OC is a new criminal in Gotham who catches the Joker's attention and they form an unlikely alliance against other villains. Maybe the OC has a special ability like mind - reading and the Joker wants to use it for his own gain.
One idea could be that the OC is a new villain in Gotham who catches the attention of both Joker and Harley. Maybe the OC has a unique power or skill that makes them a threat or an ally. For example, the OC could have the ability to manipulate minds, which Joker wants to use for his own evil plans, while Harley sees the OC as a potential friend who can understand her chaotic nature.
There's a fanfiction called 'Love in the Asylum' which delves into the idea of an OC falling for the Joker while they are both in Arkham Asylum. It shows how their relationship develops in such a confined and crazy environment. This story might be interesting as it plays with the psychological aspects of both characters.
One interesting joker reader fanfiction could be about the reader being a detective who has to face off against the Joker. The tension and mind games between them make for a great story.
There are 'dark joker fanfiction' that focus on his relationship with other villains. Maybe he forms an alliance with a new, equally dark character. They could embark on a crime spree that is not just about money or power, but about spreading pure anarchy and chaos throughout Gotham. It would be full of unexpected twists and turns.
One interesting 'Joker Naruto' fanfiction could be where the Joker's chaotic nature disrupts the ninja world of Naruto. For example, he might play mind games with the Akatsuki members, causing internal strife. Another could involve Naruto trying to understand and rehabilitate the Joker using his own beliefs in friendship and redemption. There could also be a story where the Joker somehow gets ninjutsu powers and uses them in the most unexpected and dangerous ways in the Hidden Leaf Village.
There are fanfictions that re - imagine their relationship in a different setting, like in a post - apocalyptic Gotham. In some, Harley uses her psychiatric knowledge to try and 'cure' the Joker of his madness, which makes for a really engaging read. Also, there are those that delve into their backstories more deeply, showing how they became the characters we know today.
One interesting joker and harley fanfiction could be about their origin story from a different perspective. Maybe it shows how Harley was initially drawn to the Joker in a more psychological depth. Another could be a story where they try to live a normal life away from crime, which would be a huge twist considering their usual chaotic nature.
One interesting story could be where Joker tries to turn Gotham against Batman in a very psychological way in the fanfiction. He spreads rumors and false evidence to make the citizens doubt Batman's motives.