Well, the idea of Villain Deku often involves a dark twist on the usually heroic Deku. In some fan concepts, it might start with Deku being pushed too far, perhaps by the constant bullying in his past and the overwhelming pressure of being a hero. He could start to question the hero society's values and see its flaws more clearly. Eventually, he might decide to take matters into his own hands in a more unorthodox and villainous way, using his One For All power not for the greater good but for his own sense of justice that goes against the norm.
One key event could be his break from the hero ideology. Maybe after a major hero - related disaster where the heroes' actions were questioned, Deku starts to think differently. Another might be when he first uses his power against a hero in self - defense but then realizes he can use it to make a statement. Also, forming an alliance with a known villain group could be a significant event in his journey to becoming a full - fledged villain.
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.
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.
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.
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.