I haven't come across one, but you could try looking on specialized comic websites or social media groups focused on comics. Maybe someone there knows if such a comic exists.
A 'villain deku x villain todoroki fanfiction' might focus on their backstories that led them to become villains. It could be that they were both wronged by the hero system in some way. Deku might have been rejected too many times or faced unfair treatment, and Todoroki could have some family - related issues that pushed him to the dark side. The story could then show how they form an alliance and start their villainous journey together.
The plot could involve the female villain saving Deku from a dangerous situation. She might be in the right place at the right time and use her villainous powers for good in that instance. This would then start a chain of events where Deku is curious about her motives, and she has to keep her true nature hidden while getting closer to him.
One possibility could be a story where the female villain is initially drawn to Deku's underdog status. She might secretly admire his determination to become a hero despite being quirkless at first. In this fanfiction, she could start observing Deku from afar, analyzing his every move and decision during battles or in school. This could lead to an interesting dynamic where she is conflicted between her villainous nature and her new - found admiration for Deku.
One great 'Best villain Deku fanfic' is 'Villainous Deku: The Dark Ascent'. It shows Deku turning to the dark side in a very believable way. The author does an excellent job of portraying his inner turmoil and the reasons behind his transformation. Another one could be 'Deku's Villainous Reign' which has some really intense action scenes where villain Deku battles against his former friends. It's a thrilling read.
Definitely not. Deku's character arc in the manga is centered around his growth and development as a hero. There are challenges and difficulties, but he never turns to the dark side.