To develop their relationship realistically, start with their existing dynamic. Bakugou is often aggressive towards Deku, so a slow change is needed. Maybe have them be forced to team up. As they face challenges together, Bakugou could start to respect Deku's abilities bit by bit. For example, if they are in a battle against a powerful villain and Deku comes up with a clever strategy, Bakugou might grudgingly admit Deku's smarts.
One great Bakugou x Deku fanfic is 'Unlikely Allies'. It explores their relationship in a post - war scenario where they have to work together to rebuild society. The character development is really well - done.
Bakugou could use his words. He might tell Deku that he believes in him. For example, he could say 'Deku, you may be a nerd but you're a strong nerd.' It's a backhanded compliment but it shows he has faith in Deku.
You can start by looking on popular fanfiction websites like Archive of Our Own (AO3). It has a large collection of fanfics for various fandoms, including those related to Todoroki, Deku, and Bakugou. The search function on AO3 allows you to easily filter for the specific relationship you're interested in.
Deku might be completely shocked at first. Since Bakugou has always been so aggressive towards him, he would never expect such a confession. He might just stand there, mouth agape, not knowing what to say.
One concept could be that Villain Deku manages to manipulate Bakugou into joining his side. Maybe he plays on Bakugou's insecurities or his desire for power. Another could be a world where they are both villains from the start and they form a power - hungry duo, causing chaos everywhere. A third concept might be that Villain Deku kidnaps Bakugou as part of a grand scheme to get back at the hero society that they both feel has wronged them in some way.
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.
Growth is also a prevalent theme. Both characters are on a journey of self - discovery and improvement, and fanfics usually show how they grow both as individuals and in relation to each other. For example, Bakugou learning to control his temper and Deku becoming more confident.
One common theme is rivalry. Their intense competition to be the best hero is often explored, like in many fanfics where they constantly try to outdo each other in training or in real battles. It shows their determination and drive.
Bakugou may prove his love by being protective. He might put himself in danger to save Deku. In many stories, this kind of self - sacrifice is a strong indication of love. Also, he could start to understand Deku's dreams and support him in achieving them, which is a deeper form of love than just friendship.