Todoroki’s Mom Burnt him
Todoroki Shouto has a burn mark on the left side of his forehead. He got it when his mom poured hot water on him while he was suprising her. But why did Todoroki’s mom burn his face?
Todoroki as you know is the fifth child of Endeavour. The reason he had so many kids was because he was looking for the ultimate combo that can beat All might and he thought fusing an ice quirk with fire would be the best approach.
But as fate would have it, his first four kids didn’t get equal shares of the quirks as he imagined they would have, instead each had an abundance of either element.
Todoroki was different, he received both the quirks in equal proportions. On his left side, he had fire and on the right, he had ice- a combination of these two can be deadly.
Todorki ignored his left side for years, considering how much he hated Endeavour and everything about him. Endeavour wanted to become the number one hero, despite all his efforts he couldn’t surpass All might which frustrated him to the core and made him look for alternate ways.
The solution as you know was Todorki’s mother.