You could write a fanfiction where the OC Predacon is on a mission to discover the origin of their species. Along the way, they meet various Autobots and Decepticons. The Predacon's journey could be filled with challenges and revelations about the history of the Transformers. Maybe they find out that their kind was once created for a specific purpose that has been long forgotten.
Another option is to make an OC Predacon that forms an unlikely alliance with an Autobot. This could be due to a common enemy or a shared goal. Their relationship would be strained at first because of the natural enmity between their factions. But as they face difficulties together, they start to understand and respect each other, leading to a unique friendship that defies the norms of the Transformers universe.
One idea could be to create an OC Predacon who is an outcast in their own clan. They might have different beliefs or abilities that set them apart. For example, this OC could have the power to communicate with other species in a way that other Predacons can't. This would lead to a lot of internal conflict within the clan as well as interesting interactions with other Transformers.
Give your OC Predacon a backstory. Maybe they were raised in a different environment than other Predacons. If they were found and raised by an Autobot, for instance, it would greatly influence their view of the world. This backstory can explain their motives and actions in the fanfiction. Also, consider their relationships with other characters. Do they have a rival within the Predacon clan? Or a special bond with a particular Transformer? These relationships can add depth to the character.
Power and its consequences is also a prevalent theme. The Predacon OC might have unique and powerful abilities. But these powers can attract unwanted attention from both good and bad forces. This can lead to a series of events where the OC has to decide how to use their power responsibly and deal with those who want to use it for their own gain.
One great source could be Archive of Our Own (AO3). There are numerous Predacon OC fanfictions there. You can search for 'Transformers Prime Predacon OC' and sort by popularity or kudos. Some fanfictions might focus on a Predacon OC's journey within the existing storylines of Transformers Prime, like their interactions with the main characters or how they affect the overall plot.
A Vehicon OC fanfiction could focus on their transformation into a more independent being. They might discover a hidden power within themselves that sets them apart from the other Vehicons. This new power could lead them on a journey of self - discovery and ultimately a change in their allegiance.
One interesting Predacon OC fanfiction could be about a young Predacon trying to find its place in a new world. It might face challenges from other species and have to prove itself.
One idea could be an OC who is a mechanic with a special ability to understand ancient Cybertronian technology. This character could be found by the Autobots and end up helping them repair an important artifact. They might have a backstory of being an outcast in their human community because of their obsession with machines, but in the Transformers world, their skills are highly valued.
Begin by brainstorming ideas for your Predacon OC. What makes it unique? Is it its color, its shape, or its special skills? Once you have a clear idea of the OC, start building the story around it. You can take inspiration from other Predacon stories or the Transformers universe in general. Outline the major events in the story, such as the introduction of the Predacon OC, the challenges it faces, and how it overcomes them. Remember to add some twists and turns to keep the readers interested.
One idea could be an OC (Original Character) who is a new Autobot arriving on Earth. They have a unique ability, like being able to communicate with animals. This could lead to some interesting adventures as they help the other Autobots in ways the others can't. For example, they might get help from a flock of birds to spy on Decepticons.
One idea could be an OC who is a medic that gets captured by Megatron. Megatron initially sees the OC as a tool to use against the Autobots but gradually develops an odd respect for the OC's skills and tenacity. Another plot could involve an OC who has a special power that Megatron wants to harness for his own evil plans. As he tries to manipulate the OC, the OC starts to see through his lies and tries to turn the tables on him. A third plot might be an OC from a different dimension who accidentally lands in the Transformers Prime universe and catches Megatron's attention. He's intrigued by this strange new being and tries to either recruit or destroy the OC.
One idea could be an OC Decepticon who has a unique ability like being able to control electricity. The plot could revolve around this OC trying to prove their worth to Megatron by taking on difficult Autobot missions. For example, they target an Autobot outpost that holds a powerful energy source. The OC's journey to the outpost, facing Autobot defenses and internal Decepticon rivalries along the way, would make for an exciting story.