One idea could be a story where a new maverick emerges with powers that can disrupt the energy signatures of all hunters, forcing Mega Man to find a way to adapt his own systems. Another could be a prequel story about how some of the main mavericks in the game came to be.
Mega Man himself is an obvious choice. His journey as a maverick hunter and his internal struggles with the concept of fighting former friends who have turned maverick can be explored. Another good character is Zero. His cool and mysterious nature can add a lot to a story.
Well, a plot could revolve around a young inventor in a parallel universe who discovers a way to communicate with the original Mega Man. Together, they try to find a solution to a virus that is spreading across multiple Mega Man universes, corrupting all the robotic beings. This would involve lots of action, as they have to fight their way through hordes of corrupted robots while also searching for a cure.
One idea could be Mega Man traveling back in time to stop Dr. Wily from ever starting his evil plans. He could meet a younger version of Dr. Light and work together to prevent the future disasters. Another plot could be Mega Man accidentally traveling to a post - apocalyptic future where his actions in the past led to a world ruled by machines. He then has to go back and change things.
One idea could be that Mega Man X and Nana team up to face a new, powerful enemy that neither could defeat alone. They have to combine their unique skills, like X's combat abilities and Nana's support functions.
Well, your OC could be a lost reploid from an ancient civilization. This OC might hold the key to a forgotten technology that could either save or destroy the world in the Mega Man X universe. They would have to navigate the politics and battles while trying to figure out their own origin and purpose. Also, an OC that was created by a villain but has a sense of good could be an interesting plot. This OC would constantly struggle between their programming and their new - found moral compass.
One idea could be a story where Bass has to team up with Mega Man X to face a new, extremely powerful enemy that neither could defeat alone. Maybe this enemy has the ability to corrupt the reploid's programming, forcing them to work together to find a cure as well as stop the threat.
One idea could be a crossover with the Sonic universe. Mega Man X and Sonic could team up to stop a new villain that is causing chaos in both their worlds. This would involve X's advanced weaponry and Sonic's speed working together in a high - action adventure.
One possible plot idea could be that Rock and X team up to face a new and powerful enemy that neither could defeat alone. For example, a super - advanced robot created by a long - lost mad scientist.
One idea could be that Rock travels back in time to prevent Dr. Wily from ever becoming evil. Maybe he meets a younger version of Dr. Light and together they find a way to steer Wily onto a better path. Another plot could be Rock traveling to different time periods in the Mega Man universe to collect powerful items that can help in his fight against the current threats. For example, he could go to a time when there were ancient robots with unique abilities and learn from them.
A really interesting Mega Man X fan fiction plot could be centered around a new type of Maverick that is immune to X's normal attacks. X has to go on a journey to find a way to upgrade his weaponry and adapt to this new threat. Along the way, he meets an old ally who has been in hiding and has some crucial information. Another plot could involve X being sent on a mission to a far - off planet where the Maverick virus has taken on a completely different form. He has to learn the ways of this new world to defeat the Mavericks there. And for the third one, we could have a story where X accidentally activates an ancient defense system that starts attacking both humans and Mavericks, and he has to find a way to shut it down.