Some good storylines could involve Optimus Prime and Arcee having to undercover as Decepticons. They'd have to act like the enemy, which would put a strain on their relationship but also bring them closer as they share this dangerous secret. Maybe there's a prophecy about them that they have to fulfill together. They start off not believing it but as events unfold, they realize it's true and it leads them on an epic adventure across the galaxy to save Cybertron or another planet.
One possible storyline could be them facing a powerful new Decepticon threat together. Optimus and Arcee would have to combine their skills, with Optimus using his strategic mind and Arcee her speed and agility. Another could be a story set in a post - war scenario where they are trying to rebuild Cybertron and their relationship deepens during the process. And perhaps a time - travel plot where they go back in time and have to change an event that will save Cybertron in the future.
One possible storyline could be a redemption arc for Megatron. In this fanfiction, Megatron, after countless battles with Optimus Prime, begins to question his motives. He realizes the destruction he has caused and tries to make amends. Optimus, initially skeptical, gradually sees the change in Megatron and they form an uneasy alliance to face a greater threat that endangers both Autobots and Decepticons alike.
Their relationship can be portrayed as a deep friendship with mutual respect. Optimus, as the leader, respects Arcee's skills and determination. Arcee, in turn, looks up to Optimus and trusts his leadership completely. They can also have a mentor - mentee relationship where Optimus guides Arcee in some aspects.
Well, a very frequent theme is the struggle between their duties and their feelings for each other. They are warriors first, so they have to balance their personal emotions with their responsibilities towards their team. Also, the theme of growth in their relationship is common. They start from a certain point and as the story progresses, their bond deepens in different ways.
Romance is also a theme, though it can be a bit tricky in the context of Transformers. Writers often explore the emotional connection between Arcee and Optimus Prime, how they might have a deeper understanding of each other that goes beyond just comradeship.
One great storyline could be a story where Megatron and Optimus Prime are forced to team up against a greater threat from another universe. They have to put aside their differences and learn to trust each other. Another could be a pre - war story, exploring their relationship before they became enemies, perhaps they were once friends or comrades. A third could be a story where they are both stranded on a strange planet and have to rely on each other's unique abilities to survive and find a way back home.
One great fanfiction could be about Optimus and Arcee going on a dangerous mission together. They face numerous challenges, like battling a powerful new Decepticon. Their teamwork and trust in each other are put to the test. Arcee's speed and agility combined with Optimus' strength make them a formidable duo. Along the way, they might have some deep conversations about the future of their race and their place in the war.
Another could be a story set in a post - war scenario. Optimus Prime is trying to rebuild Cybertron, and Ratchet is right there with him. They encounter various challenges like lack of resources and dissent among the remaining Cybertronians. Their friendship is strained but ultimately grows stronger as they work through these problems.
Another plot could be set in a post - war scenario. The Autobots are rebuilding their world, and Optimus Prime and Arcee are tasked with different aspects of the reconstruction. However, they keep finding excuses to work together. As they do, they gradually fall in love while also dealing with the trauma of the war and the challenges of creating a new future for their kind.
There's a fanfic called 'Arcee's Trust'. In this, the relationship between Optimus and Arcee is explored in a very unique way. It shows how their bond grows over time. The author does a great job of writing their dialogues, which seem very in - character. It's a great read if you like stories that focus on character development.
Perhaps there's a story where Optimus and Megatron are both stranded on a desolate planet. Without their armies and with limited resources, they have to rely on each other to survive. As they struggle to find a way off the planet, they start to understand each other better. Megatron realizes that Optimus isn't just a naive idealist and Optimus sees that Megatron has reasons for his actions that are more complex than just pure evil.