Maybe the OC is a time - traveler who has come to prevent Cell from reaching his perfect form. They try to disrupt his plans at every turn. This could involve the OC teaming up with the Z - Fighters in some ways, and there would be a lot of action and strategy involved in their attempts to outwit Cell.
The OC could be a powerful alien with unique energy - based powers. They encounter Cell and, instead of fighting right away, they engage in a battle of wits. The OC tries to convince Cell that there are better ways to achieve his goals than destruction. This could explore themes of redemption and self - discovery for Cell.
One idea could be that the OC is a powerful being from another dimension and Cell is intrigued by their power. He tries to either absorb them or form an alliance to take over the universe together. Another plot could be the OC has a special ability to control Cell's cells, creating an interesting power dynamic between them. And a third could be that the OC is a time - traveler who knows Cell's future and tries to change his path in the DBZ universe.
One idea could be that the OC is a new student at Barden University and has an amazing, unique vocal talent that catches Donald's attention during auditions for the a cappella groups. Maybe the OC has a secret past related to music that gradually unfolds throughout the story, and Donald helps the OC overcome some insecurities related to it.
One idea could be that Frieza and Cell team up to take over the universe in a new and unexpected way. They combine their powers and intelligence to outwit all the other powerful beings.
One idea could be that Cell somehow gets a second chance at life and instead of being a villain, he tries to team up with Goku. They could go on adventures together across different universes, facing new threats and learning from each other. Goku could teach Cell about the value of protecting the innocent, and Cell could show Goku some of his scientific knowledge about power levels and energy manipulation.
One idea could be that the OC is a healer who stumbles upon Frankenstein's monster in the woods. The OC decides to help the monster, despite the danger, and they form an unlikely bond. This could lead to a story of redemption for the monster and a journey of self - discovery for the OC.
Maybe the OC is a scientist who has developed a device that can temporarily steal The Flash's speed. At first, the OC uses it for personal gain, but then realizes the chaos it's causing in the city. They then team up with The Flash to take down other villains who are after the device. Or, the OC could be a meta - human with the ability to see the future in flashes. The Flash initially doesn't trust the OC, but as they start to have the same visions, they have to work together to prevent a major disaster from happening.
The OC could be a psychic who is unknowingly drawn to Derry because of Pennywise's presence. Their psychic powers allow them to sense Pennywise's energy but not fully understand what it is at first. As Pennywise tries to manipulate the OC, the OC starts to fight back using their psychic abilities, creating a battle of wills and powers that could span across different dimensions within Derry, from the sewers to the abandoned houses and the mindscapes of both characters.
The OC could be a researcher studying digimon behavior. Renamon becomes the subject of the study. At first, Renamon is very guarded around the OC. However, as the OC shows genuine respect for Renamon and her kind, Renamon begins to open up. They then embark on a journey to discover more about the history of digimon, with their relationship growing stronger along the way.
Well, an interesting plot could involve an OC that is a transfer student, just like the protagonist. But this OC has a hidden past related to the Metaverse. Maybe they were experimented on by a shadowy organization in their home country, and this gives them a different perspective on the Metaverse compared to the Phantom Thieves. Their goal could be to find out who was behind those experiments and get revenge. Along the way, they form a bond with the group and learn new ways of using their powers.
One idea could be that the OC is a new Keyblade wielder who meets Ventus during his training. They start as rivals, constantly competing in battles and challenges. But as they face a powerful enemy together, they realize their combined strength and start to develop feelings for each other.