One possible fanfiction could be that they are brothers separated at birth. Megatron is raised in a harsher part of Cybertron, which shapes his more aggressive views, while Optimus Prime is raised in a more diplomatic environment. Their reunion could be a turning point for the entire Cybertronian civilization.
In a fanfiction where they unite, it could start with a common threat that neither side can face alone. For example, an alien race invades Cybertron. Megatron and Optimus Prime realize that their brotherly bond is stronger than their differences. Together, they could form a new strategy, using both Autobot and Decepticon forces in a coordinated way to repel the invaders.
I'm not an expert in anime or movies, and I don't have enough information to answer this question. However, according to what I know about the Transformers plot, the scene of the fight between Prime and Megatron on the moon is not a plot of an anime or movie, but a plot of a Transformers comic or novel. In the Transformers comics and novels, Prime and Megatron often fought on different planets, some of which even involved the moon.
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.
Optimus Prime is shown as extremely powerful in comics. His strength lies not just in his physical might but also in his leadership and determination. He can overcome seemingly impossible odds and lead his team to victory.
Optimus Prime is extremely powerful in the comics. His strength is shown through his ability to battle against powerful Decepticons and protect Earth. He has advanced weaponry and a never-give-up attitude that makes him a formidable character.
Fanfiction about them often allows for different interpretations of their characters. Writers can take their basic traits from the original source and expand on them. For example, exploring Elita One's past more deeply and how it affects her relationship with Optimus Prime. This gives a fresh perspective to the well - known characters.
Optimus Prime was originally a regular Autobot named Orion Pax. He worked in the Iacon Archives. One day, he was caught in the middle of a battle between the Autobots and Decepticons. After being rebuilt by Alpha Trion, he became Optimus Prime, a great leader of the Autobots, and began his long - standing fight against the Decepticons.