A prevalent theme is redemption. Sometimes the OC is there to redeem the Riddler from his villainous ways. Also, the theme of identity is common. The OC may be trying to find their own identity while being in the Riddler's world, or they may be helping the Riddler figure out his true self.
A lot of 'Penguin x Riddler fanfiction' has the theme of power struggle. Since they are both strong - willed villains, they could be vying for control in Gotham's criminal hierarchy. And sometimes, there's a theme of unexpected friendship or partnership that develops between them in the face of common enemies.
One common theme could be the exploration of the complex relationship between the two characters. Another might be the power dynamics.
His relationship with other villains or heroes is also common. For example, his rivalry with Batman or possible alliances with other Gotham criminals. In Telltale Games' universe, this can be explored in unique ways. Fanfiction may show how the Riddler tries to gain an upper hand over Batman, or how he interacts with characters like Catwoman or Penguin in this particular game setting.
One idea could be to explore the Riddler's origin story from the perspective of your original character (OC). Maybe your OC is a detective trying to solve the mystery of the Riddler's first crime spree. Another idea is to have your OC be a sidekick of the Riddler, either willingly or by being forced into it. They could then have a complex relationship where the OC tries to influence the Riddler's actions for better or worse.
Well, in transformers oc x oc fanfiction, one of the prevalent themes is self - discovery. These original characters are often in a world full of powerful and well - established transformers, and they have to figure out who they are and their place. Power struggles can also be a theme, as the ocs might be vying for a position or trying to prove themselves. Survival in the often - dangerous transformers' world is yet another common theme. For example, ocs might have to face off against powerful enemies or deal with the aftermath of a big battle.
Friendship is a common theme. Just like in the original movies, OCs in fanfiction often form strong bonds with the existing characters. For example, an OC might help Alex when he's feeling homesick for the zoo.
One common theme is friendship. Often, the OC forms a strong bond with Margaery, either helping her through difficult times or being helped by her. Another theme is political intrigue. Since Margaery is a major player in the political scene in the 'Game of Thrones' universe, the fanfictions usually involve the OC getting caught up in the plots and schemes.
One common theme is redemption. Often, the oc has a troubled past and through their interactions with the Mandalorian, they seek to atone for their previous actions.
The theme of redemption is also present. The OC may have made mistakes in their past, and through their adventures with the Winchesters, they seek to redeem themselves. This could be related to accidentally causing harm in the supernatural world or having a dark past that they are trying to overcome.
Power dynamics are quite common. The OC may have unique powers that either complement or clash with Vergil's. Also, the theme of redemption can be seen. Vergil has his own demons, and the OC can be a part of his path to redemption. For example, in some fanfictions, the OC's positive influence slowly changes Vergil's view of the world and himself. In addition, the exploration of different worlds or dimensions is also a theme. If the OC is from another place, it adds an element of discovery and adventure to the story.