One common theme is discovery. Raf, being a curious human, often discovers something about Dark Energon. Another theme is danger. Dark Energon is always presented as a very dangerous substance in these fanfictions.
One popular fanfiction might be 'Raf's Encounter with Dark Energon'. It delves into how Raf, with his unique connection to the Cybertronians, stumbles upon Dark Energon and the chaos that ensues. The story shows his attempts to understand the power and how it affects the Autobots and Decepticons around him.
He might interact with it in a curious way at first, not fully understanding its danger. For example, he could be drawn to it because of its mysterious properties.
Some fanfictions might explore the origin of Dark Energon in relation to Raf. Perhaps there are hidden secrets about Raf's past that are somehow connected to the Dark Energon. This could lead to a whole new adventure where Raf has to discover his true identity while dealing with the perils of Dark Energon.
One possible fanfiction could be about Bumblebee stumbling upon a cache of Dark Energon. Maybe he initially doesn't realize the danger it poses. He could be curious and start investigating it, which then leads to some strange effects on him, like his systems glitching in new and unexpected ways. This could put him in a precarious situation where his Autobot friends have to figure out how to reverse the effects before it's too late.
When Raf gets hurt in Transformers Prime fanfiction, it could lead to the Autobots becoming extremely protective. For example, Bumblebee might stay by his side constantly, not wanting to leave him alone even for a moment. They would also be more determined to fight against the Decepticons, seeing Raf's injury as a sign that they need to step up their efforts to protect the humans.
One possible fanfiction could be about Dark Optimus Prime's origin. Maybe he was corrupted by a powerful dark energy source in the Transformers Prime universe. This could lead to him having different goals and motives compared to the regular Optimus Prime, like ruling Cybertron with an iron fist instead of leading it to peace.
Maybe a fanfiction where Dark Energon is being used to power a new super - weapon, and Bumblebee has to infiltrate the Decepticon base to stop it. Along the way, he discovers some secrets about the origin of Dark Energon and its connection to the Transformers' past. This would be an exciting plot full of mystery and adventure.
You can try searching on popular fanfiction websites like Archive of Our Own (AO3) or FanFiction.net. These platforms usually have a wide range of Transformers - related fanfictions, including those involving Bumblebee and Dark Energon.
A plot idea could be that Bumblebee is the only one immune to the negative effects of Dark Energon. The Autobots use this to their advantage and send him to infiltrate a Decepticon base where Dark Energon is being weaponized. He has to pretend to be under the influence of Dark Energon while gathering intel and sabotaging the Decepticon's plans.