The themes could include the concept of nurturing. Just as a pregnancy involves nurturing a new life, in the fanfiction, Optimus Prime and Arcee could be nurturing a new idea or technology for the Transformers. It could also touch on the theme of sacrifice, as they might have to make sacrifices to ensure the successful 'birth' of whatever the 'pregnancy' represents. There could also be a theme of unity, as they work together towards this new development that the 'pregnancy' symbolizes.
One possible theme could be about creation and new beginnings. Maybe they are creating a new type of Transformer, and the process is symbolized as a pregnancy. Another theme could be about the bond between them growing stronger as they 'await' this new creation.
It's possible. Fanfiction often takes existing characters and gives them new storylines. In the case of Optimus Prime and Arcee, a 'pregnant' fanfiction could be about them having a new form of life or a project that they are nurturing together, which is presented as a pregnancy - like concept. You may need to do some digging through various fanfiction communities and websites to find one that suits your taste and is suitable for all viewers.
The theme of sacrifice often appears in fanfictions about them. They are willing to put themselves in harm's way for the greater good. This could be shown in a scenario where they have to sacrifice a strategic position to save a group of innocent Autobots. Also, the theme of redemption can be explored, especially if a character from their past resurfaces and they have to decide whether to forgive or not.
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.
One possible fanfiction could be about Arcee and Optimus teaming up for a dangerous mission. They might face a powerful new enemy that neither of them has encountered before. Their combined skills and trust in each other would be crucial in overcoming the challenges. For example, Arcee's agility and Optimus' strength could be used in a complementary way to defeat the foe.
Perhaps a fanfiction where Arcee has to save Optimus Prime from a mind - controlling device. She has to fight against his altered self and find a way to break the control. This would show her determination and loyalty to Optimus.
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.
Perhaps a fanfiction where Arcee and Optimus are transported to an alternate dimension. In this new world, they have to figure out how to get back home while also dealing with the strange new rules and inhabitants. They might find that their relationship is put to the test as they face unfamiliar and often dangerous situations. They could also learn new things about each other that they didn't know before.
One great Optimus Prime and Arcee fanfiction could be about them teaming up on a dangerous mission. They might face a new, powerful enemy that forces them to rely on each other's unique skills. Arcee's speed and agility combined with Optimus Prime's strength and leadership could make for an exciting story.
One possible plot could be that during a dangerous mission, Optimus Prime and Arcee get separated from the rest of the team. As they struggle to survive and find their way back, they rely on each other more than ever. This shared experience deepens their bond, and eventually, they share a kiss as a sign of their new - found closeness.
One possible theme could be about Rapunzel's journey into motherhood and how she overcomes her fears. For instance, she might be worried about being a good mother since she was locked away for so long and didn't have a normal upbringing herself.