One possible fanfiction could be about Optimus Prime and Megatron having to team up against a greater threat. Maybe an ancient evil from Cybertron's past resurfaces that is so powerful that their usual enmity has to be put aside. They start off distrusting each other but as they face battles together, they gradually come to respect the other's fighting skills.
A fanfiction could focus on a time when Megatron and Soundwave are separated. Maybe Megatron has been captured by the Autobots, and Soundwave is left to lead the Decepticons in his absence. Soundwave, who is not used to being in the spotlight, has to make difficult decisions. He has to figure out how to rescue Megatron without sacrificing too many of their troops. Meanwhile, Megatron is facing his own challenges in captivity, perhaps having to deal with Optimus Prime's attempts to make him see the error of his ways. This situation could create a lot of tension and drama in the fanfiction.
First, think about your OC. Decide on their appearance, personality, and special abilities or skills. For example, if your OC is a strong fighter, how did they become so skilled? Then, consider how they will interact with Megatron. Will they be an enemy right away or will there be some initial misunderstanding? Next, plan the setting. Is it on Cybertron? Or on Earth during the battles between Autobots and Decepticons? Start with a strong opening that grabs the reader's attention, like a battle scene where your OC first encounters Megatron.
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.
Fanfiction about them can explore different universes and scenarios. For example, what if they were raised together? How would their relationship be different? It gives fans a chance to play with the established lore and create new and exciting stories that the official Transformers storylines may not explore. It also allows for deeper exploration of their motives and personalities.
One common theme is redemption. Megatron has a long history of being a villain, and in many fanfictions, Bumblebee becomes the catalyst for his possible redemption. For example, in stories where they are stranded together, Bumblebee's positive attitude might start to make Megatron question his actions.
One challenge is character consistency. Megatron is typically a ruthless villain, so making his relationship with Arcee believable while still maintaining his core character traits can be difficult. For example, he can't suddenly become a completely good character just because he has feelings for her.
One common theme is redemption. Megatron trying to make up for all the bad things he has done. Another theme could be the power of friendship or unexpected alliances. For instance, he might form an alliance with an Autobot he once hated.
Yes, there are some really interesting fanfictions out there. Some explore Megatron's change through his complex relationships, like his rivalry with Optimus Prime. The change might be triggered by a major event in the story, such as seeing the destruction he has caused and having a moment of self - realization.
Perhaps there could be a story where an ancient Cybertronian threat resurfaces. Megatron and Soundwave must team up with some unlikely allies, like a group of Autobots who also realize the severity of the situation. Throughout the story, Megatron and Soundwave would have to navigate their relationship with these former enemies while also dealing with the new threat. Their different personalities and motives would add depth to the story as they try to protect Cybertron together.