One popular Bakugou truth quirk fanfic could be 'The Truth Unveiled'. In it, Bakugou's truth quirk might be explored in a way that reveals his innermost thoughts and feelings towards his classmates and his own insecurities. This could lead to some really interesting character development and interactions.
Some fanfics depict his truth quirk as being triggered by strong emotions. So when he gets really angry or excited, he can't help but tell the truth. This can lead to some hilarious or very intense situations. For instance, during an argument with Deku, his quirk activates and he reveals his true feelings of respect and rivalry towards him all at once.
Midoriya is very likely to be in it. He and Bakugou have a complex relationship. Midoriya could be the one who either challenges Bakugou to face his fears or is there to support him in the process. Their rivalry - turned - friendship can play a big role in Bakugou's journey of facing his fears.
He could become more empathetic. If the quirk makes him experience something difficult like the pain of others or a disability, it might make him more understanding of those around him who are less powerful or have faced hardships.
It could be Voldemort. Voldemort might use Harry's love as a weapon against him. He could either kill her or turn her against Harry. Another possibility is Draco Malfoy. Maybe Draco tricks Harry's love into thinking he's a better choice. Or it could be a new, unknown dark wizard who targets Harry through his love.
In fanfiction, Izuku often has unique ways to cultivate his quirk. One common scenario is that he focuses on intense physical training. Since his body was initially not as strong as it could be to handle his powerful quirk, he might do a lot of strength - building exercises like weightlifting and running. This not only helps him control his quirk better but also increases his overall combat capabilities.
Well, Deku does lose his quirk. However, this event leads to new developments and challenges for him. It's a crucial plot twist that adds depth to the story.
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.