In 'hero deku meets villain deku fanfiction', character development is key. Hero Deku may develop by realizing that the line between hero and villain is not always so clear. He could become more complex, not just seeing things in black and white. Villain Deku could develop by having his long - held grudges and beliefs challenged. For instance, if he believed that power was the only thing that mattered, Hero Deku could show him the value of friendship and teamwork. As they interact, their personalities could change, with Hero Deku becoming more street - smart and Villain Deku becoming more open - minded. This would create a more nuanced and interesting story.
For Hero Deku, his development could be shown by how he reacts to seeing his dark self. He might start to question his own beliefs and actions. For Villain Deku, his development could be in the form of a possible redemption arc. Maybe he starts to see the error of his ways through his interactions with Hero Deku. For example, if Hero Deku shows him kindness or understanding that he never received before.
Villain Deku might start to question his villainous ways. Meeting Hero Deku could make him see the good in heroism. Hero Deku, on the other hand, could become more empathetic towards those who turn to villainy. He might realize that there are reasons behind it and not all villains are just 'evil' for the sake of it.
One possible plot could be that Villain Deku is on a mission to undermine the hero society and crosses paths with Hero Deku. They engage in a fierce battle where Villain Deku taunts Hero Deku about his ideals. In the end, Hero Deku manages to get through to a small part of Villain Deku's conscience, leaving him with some doubts about his villainous path.
A possible plot is that Villain Deku has a plan to destroy a major hero institution, and Hero Deku has to stop him. But when they meet, Hero Deku realizes that Villain Deku was once like him, full of hope. This makes Hero Deku hesitant to fight at full force. Or perhaps Villain Deku has kidnapped someone close to Hero Deku, and during the rescue mission, Hero Deku tries to convince Villain Deku to change his ways. Also, they could be from alternate universes where the roles are reversed, and they are forced to interact and learn from each other.
In fanfiction, Villain Deku's development can be much more complex. He might be pushed to the villain side by circumstances like the death of a loved one and the hero society's failure to do anything about it. This is different from the original where he has a clear path of becoming a hero with support from his mentors and friends. His relationships also change drastically. Instead of having friendly rivalries with Bakugo and others, he may see them as enemies to be defeated.
For Villain Deku, start by showing his gradual descent into villainy. Maybe he starts having doubts about the hero system and those doubts fester. For his relationship with Kacchan, show how his feelings change from friendship (or rivalry) to something more complex. For Kacchan, show his initial shock and anger at Deku's turn. Then, have him start to question if there was something he could have done to prevent it. As the story progresses, he could start to see the good in Deku again.
Toga could be an ally. Since she has her own complex relationship with the idea of heroes and villains, she might find Deku's transformation interesting. She could provide some of her unique skills, like shape - shifting, to help Deku in his villainous plans. Additionally, Twice might also join them because of his loyalty to Toga and his own sense of being an outcast in the hero world.
Bakugo would likely be furious. He'd feel betrayed and would probably be the first to attack Deku, yelling at him about how he's thrown away everything they've worked for. Uraraka might be more empathetic. She'd try to understand what drove Deku to become a villain and hope there's a way to bring him back to the side of good.
Their relationship could start with mutual self - interest. They both recognize the power and chaos the other can bring. For example, Toga's ability to transform could help Villain Deku infiltrate places, and he can offer her protection in return.
The relationship could start with hatred. Bakugou may initially be enraged that Deku has become a villain. But as time passes, he starts to see the reasons behind Deku's transformation, which could lead to a more complex relationship.
In 'deku meets future deku fanfiction', perhaps the future Deku warns the present one about upcoming threats. He could tell him about villains he'll face in the future and how to defeat them. This would give the present Deku an edge in his battles and also in his growth as a hero.