With fire and ice, Todoroki has become one of the most recognizable characters in My Hero Academia. But why does Todoroki have two quirks?
Todoroki has two quirks because he’s the child of a “quirk marriage.” His father, Endeavor, forced a woman with an ice quirk to marry him so they could have a child with two quirks. Endeavor couldn’t surpass All Might, so he wanted a strong and unique child to do it for him.
Endeavor leveraged his wealth and fame to force Todoroki’s mother’s family to agree. It was all done in an effort to get his hands on her quirk for his backup plan; living vicariously through Todoroki.
Todoroki Explains to Deku Why He Has Two Quirks
Before Todoroki and Deku squared off during the combat portion of the Sports Festival, the two spoke alone. Todoroki asked if Deku had any connection to All Might. Deku dodged the question, but Todoroki then went on to explain how he ended up with two quirks.
Todoroki explained that his father is “… a powerful bastard who only thinks of becoming stronger.” Endeavor had gone all out to make a name for himself as a hero, but he could never beat All Might on his own. His backup plan was Todoroki.
Quirk marriages. You’ve heard of them, right? They started becoming a problem during the second or third generation after quirks appeared. Strong individuals would choose a partner and force them into marriage for the sole purpose of passing on a strengthened version of their own quirk.
Todoroki to Deku | Chapter #31
Earlier generations lacked ethics, Todoroki said. Endeavor used his wealth and fame to force Todoroki’s mother’s family to agree to marriage. This was all done to get his hands on her quirk and create a powerful successor who could usurp All Might.
So that’s the answer. Todoroki has two quirks because he’s the son of a “quirk marriage.” This means that his father seeked out and forced a powerful quirk user to marry him so that his child could bear two separate quirks.