Perhaps in the crossover fanfiction, the dark energy in the Mass Effect universe has some strange effect on Asura. It either amplifies his wrath to uncontrollable levels or gives him new powers. Meanwhile, the Asari, with their biotic abilities, try to form a connection with Asura to understand his nature. This connection could lead to a mutual understanding between Asura and the Mass Effect races, and together they work towards a common goal, like saving a planet that is on the verge of destruction due to a combination of Mass Effect threats and something related to Asura's past.
Asura and Shepard would be really interesting. Shepard is used to leading and making tough decisions, while Asura is driven by his wrath. Their different personalities would create a lot of tension and also great moments of cooperation. For example, when facing a tough battle, Shepard might try to come up with a strategic plan, but Asura could just charge in with his brute force. They would have to learn to work together.
One possible plot could be that Asura finds himself in the Street Fighter universe due to some mysterious rift. He then gets involved in the various battles and rivalries. Maybe he initially clashes with Ryu, thinking he is a threat, but later they realize they have a common enemy that is causing chaos in both their worlds.
Well, it could be about Ben using his alien forms to fight alongside the Mass Effect characters against a common enemy like the Reapers. Maybe his Four Arms form could be used for brute strength in hand - to - hand combat with the husks.
The plot could involve a tournament in the Street Fighter world where Asura is an unexpected entrant. His over - the - top powers would shock the other fighters. Maybe some of the Street Fighter characters would be intrigued by his raw power and try to learn from him, while others would be jealous. This could lead to various matchups and character development for both Asura and the Street Fighter cast.
One possibility could be that the races from Mass Effect come to the now - abandoned Earth and start exploring the ruins. They might find remnants of human technology and culture that could change their understanding of the humans. For example, they could discover old military bases with advanced weaponry blueprints that could be used in their own conflicts.
Well, the plot could involve Noble Six being somehow transported into the Mass Effect universe. Maybe they could team up with Shepard. Noble Six's combat skills would be a great asset in the fight against the Reapers.
One possible plot could be Lara Croft discovers a Prothean artifact during one of her adventures. This artifact has a connection to the Mass Effect universe, perhaps it contains data about the Reapers. She teams up with Commander Shepard to figure out how to use this information to stop the Reapers or some other threat that is starting to cross over from the Mass Effect universe into her world.
One exciting plot possibility could be Asura facing off against Darkseid. Their immense power levels would make for an epic battle. Asura's rage and his unique combat style against Darkseid's Omega Beams and his tyrannical rule would be a sight to behold. Another could be Asura teaming up with Superman. They both have a strong sense of justice. Asura could learn about a different kind of heroism from Superman, and together they could take on a common enemy like Doomsday. It would be interesting to see how their powers combine and what kind of dynamic they would have.
One popular theme is the crossover with other action - based video games. For example, a crossover with God of War could be interesting as both have powerful and somewhat angry protagonists. The clash of their worlds and fighting styles would make for an exciting story.
A new character could be created as the main antagonist. This character could be a being from a dimension that has been observing both the Asura's world and the Street Fighter universe. It realizes that by causing conflict between the two, it can absorb the energy of destruction and chaos. So it starts manipulating events, pitting Asura against the Street Fighter characters at first, and then revealing itself as the true source of all the problems.