One way Bakugou could prove his love in the fanfic is by sharing his own insecurities with Deku. This is a very intimate act as it shows that he trusts Deku completely. He may also show his love by simply being there for Deku during tough times, listening to him and offering advice or just a shoulder to lean on.
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.
In the fanfic, there might be a moment where Bakugou is seriously injured but still tries to encourage Deku to keep going and not worry about him. This selfless act of putting Deku's well - being and future above his own pain is a strong indication of his love. Also, when Bakugou starts to train with Deku privately to help him improve his skills, it shows that he wants to see Deku succeed and is willing to invest his own time in it.
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.
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.
Some characters might try to understand Deku's motives. Kirishima, who was close to Bakugou, would be angry at first but might also try to find out if there were any extenuating circumstances. However, many would be afraid of Deku, seeing him as a threat now that he has killed one of their own.
At first, it could be extremely strained. Deku might be terrified of Bakugou and avoid him at all costs. But as the story progresses, if Bakugou realizes his mistake, he could start trying to make it up to Deku. Deku, on the other hand, might be hesitant to accept Bakugou's apologies at first, but over time, they could start to rebuild a more positive relationship based on mutual respect.
Bakugou's character might develop by becoming more empathetic. At first, he may be his usual brash self, but as he sees Deku in distress, he starts to understand the importance of being kind. So he grows in his ability to show compassion.
Deku might be initially shocked. He's used to Bakugou's aggression, but an actual injury is different. He could be in pain and disbelief at first. Then, he might try to downplay it, especially if he doesn't want to cause trouble for Bakugou, because Deku is generally a very forgiving character.
One possible motive could be a long - held grudge that has festered over time. Maybe Bakugou's constant bullying in their past finally pushed Deku over the edge. Another could be some sort of mind - control or dark influence that made Deku act out of character.
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.
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.