One plot idea could be that Todoroki is kidnapped by a villain who wants to use his powerful quirk for their own evil plans. His friends then embark on a dangerous rescue mission. Another could be that it was a case of mistaken identity and Todoroki has to figure out how to escape while also dealing with the kidnappers' demands. Or perhaps Todoroki is kidnapped by a group who wants to study his unique genetic makeup related to his quirk.
The story could end well if Todoroki is successfully rescued by his friends. They could have a big celebration and Todoroki could thank them for their efforts. He might also grow stronger from the experience, both in his quirk control and in his relationships with his friends.
A common plot twist could be that the kidnapper is actually someone he knows, like a long - lost relative with a grudge. This adds an element of shock and makes the story more complex.
One interesting 'Shoto Todoroki kidnapped' fanfiction could be where his friends from UA have to go on a rescue mission. They use their quirks in unique ways to track him down. For example, Deku might use his enhanced strength and ability to analyze the situation to find clues.
His friends would probably take care of him. Midoriya would be very eager to help, using his kind-hearted nature. He would make sure Todoroki is fed and comfortable.
One idea could be that all his friends at UA plan a surprise birthday party for him. They decorate the common room with his favorite colors, blue and red. Another plot could be Todoroki spending his birthday with his family, trying to reconcile with his father on this special day. Maybe he receives a heartfelt gift from his mother that has a deep emotional significance.
Todoroki's character development in time travel fanfictions can be quite profound. He may start as a somewhat aloof character, but through time travel, he begins to understand the importance of relationships more deeply. When he travels back and witnesses the relationships he could have had or lost, it makes him cherish the ones he has in his original timeline. His view of heroism also evolves. He realizes that being a hero isn't just about using his powers but also about making the right choices at the right time, which is especially highlighted when he has to make decisions that could change entire timelines.