Optimus Prime could fit in as a powerful ally. He would be like a super - powered being in the RWBY world. His presence could shake up the power balance. Maybe he arrives through a portal and immediately starts helping the RWBY teams fight the Grimm. He could be seen as a symbol of hope, much like the Huntsmen and Huntresses are in RWBY.
Well, a cool crossover would be a race - related one. Optimus Prime is known for his speed in vehicle mode. He could participate in a race in the RWBY world, perhaps against some of the high - speed vehicles or characters there. This would not only be an exciting event but also a chance for the two different universes' cultures to clash and interact. Also, there could be a story where Optimus helps RWBY characters understand the concept of teamwork in a new way, based on his own experiences with the Autobots.
Optimus Prime's strength and ability to transform could be combined with RWBY's unique semblances. For example, Ruby's speed semblance could be enhanced when she rides on Optimus in his vehicle form. Or Yang's strength semblance could be amplified when she teams up with Optimus in a fight, using his power as a boost.
Well, a cool crossover in Optimus Prime x RWBY fanfiction could be the Autobots' technology being integrated into the RWBY universe. For example, Optimus might help Ruby upgrade her Crescent Rose with some Cybertronian tech. Also, the Autobots' code of honor could influence the huntsmen and huntresses in RWBY. Maybe there could be a story where Optimus and the RWBY team have to travel through different dimensions to stop an evil force that threatens both their worlds.
Optimus Prime would likely be a very calm and noble presence among the RWBY characters. He might be seen as a sort of mentor figure, especially to Ruby, who is also a leader in her own right. His stoic nature could contrast with the more emotional and impulsive behavior of some of the RWBY characters.
One possible fanfiction could be about Sentinel Prime and Optimus Prime having to work together to save Cybertron from a new, powerful enemy. They might start off with some differences in their approaches but gradually learn to combine their strengths.
Once upon a time, Optimus Prime was resting after a long day of protecting the universe. He parked himself in a quiet corner of the Autobot base. His optics dimmed as he thought about all the battles he had won and the friends he had made. The other Autobots moved quietly around him, knowing he needed his rest. And as he drifted off to sleep, his dreams were filled with visions of a peaceful future for all.
One idea could be that Optimus Prime somehow ends up in the RWBY universe and teams up with Team RWBY to fight a common enemy. Maybe a new type of Grimm that is attracted to his Cybertronian energy.
Baby Optimus Prime's character can be developed by exploring his relationships. If he has a mentor figure among the Autobots, his interactions with that character can shape him. He might look up to this mentor and try to imitate their good qualities. His relationship with other baby Transformers or younglings can also be important. He could learn about sharing, cooperation, and friendship through these relationships. Additionally, his discovery of his own strength, both physical and mental, can be a key part of his development. For instance, when he first realizes he can lift a small object that others thought was too heavy for him, it gives him confidence.
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.