Perhaps a fanfiction where Bumblebee gets severely damaged in a battle. Optimus Prime then has to take on the role of not just a leader but also a mentor to help Bumblebee recover both physically and mentally, and in the process, they form an even deeper bond.
Well, one possibility could be a story where Optimus Prime and Bumblebee face a new threat together. Maybe they get separated from the rest of the Autobots and have to rely on each other more than ever. The 'lemon' aspect could be added in a way that shows their strong bond, like a really emotional moment where they save each other from a dangerous situation and their friendship deepens in a way that's full of heart and a bit of that 'lemon' - like a very pure and intense connection.
One great fanfiction could be 'The Bond Beyond Bots' which explores their relationship in a post - apocalyptic world. It shows their deep connection and how they support each other through tough times.
One plot could be that they are on a mission in an unknown planet. They get lost and have to find their way back. During this time, they rely on each other's skills and start to understand each other on a deeper level. The lemon part could be the trust they build which is like a warm, fuzzy feeling in their relationship. For example, Bumblebee might find a way to communicate better with Optimus Prime during this tough time, and Optimus Prime in turn, protects Bumblebee more fiercely.
Another way is to join Transformers - related forums. Fans often share their favorite fanfictions there. You can ask specifically for Bumblebee and Optimus Prime love stories and someone will surely point you in the right direction.
Some fanfictions show Optimus Prime as a father figure to Bumblebee. His wise and patient personality helps guide Bumblebee's growth. Bumblebee, in turn, with his loyalty and enthusiasm, gives Optimus hope and reminds him of the good they are fighting for. It's a very heartwarming interaction.
In fanfiction, their relationship could also be explored on a more personal level. Maybe they have a long - lost love story. They could have met before the war and had a deep connection that was put on hold due to the chaos of the war. Writers might create scenarios where they rekindle their relationship while still leading the Autobots.
The other characters in the Highschool DxD world would have a wide range of reactions. The angels might see Optimus as an unknown factor and be a bit suspicious. The fallen angels might try to manipulate the situation to their advantage. And the normal human students would be terrified at first. But as the story unfolds and they see Optimus Prime's noble actions, they could start to look up to him as a hero, much like how the Autobots are seen as heroes in their own universe.
The beauty of Optimus x Bumblebee fanfic often lies in how writers re - imagine their interactions. In many of these stories, Optimus serves as a mentor to Bumblebee, and their relationship evolves from a simple leader - follower dynamic to something more like family. For example, in some fanfics, Bumblebee might get injured and Optimus has to make a difficult decision to save him, which showcases their deep connection.