Once upon a time, there was a Todoroki sister OC named Hana. She had the same white and red hair as her brother Shoto. Hana was often in the shadow of her powerful siblings. But she had a unique power of her own - the ability to manipulate ice and fire separately, not just together like Shoto. One day, she decided to prove herself. She entered a hero competition at school. At first, everyone underestimated her. But as the challenges went on, she showed her true strength, impressing everyone with her precise control over her powers.
The theme of identity is quite common. Touya Todoroki has a complex identity, being who he is with his powers and his family history. Fanfictions often explore how he defines himself. Another theme is revenge. Some fanfictions have him seeking revenge against those who wronged him in the past. And the theme of hope is also there. Despite all the hardships he has faced, many fanfictions show him holding onto hope for a better future, for himself and for those he cares about.
One characteristic is the creative combination of Todoroki's powers. For example, in a crossover with the X - Men, his ice and fire powers are compared and contrasted with the mutants' abilities. Another is the exploration of his personality in different settings. In a crossover with Studio Ghibli worlds, his stoic nature might be challenged by the more whimsical environments. Also, a lot of popular ones involve Todoroki forming unique relationships, like in a crossover with the Pokemon world where he might form a bond with a fire - type Pokemon.
One common theme is rivalry. Bakugo's aggressive and competitive nature against Todoroki's more reserved yet powerful self makes for an interesting dynamic. Another theme is friendship development, as they often start off at odds but then find common ground.