Since he was born, Shouto had known fire and ice.
Fire symbolized his father, in little Shouto's eyes. It was powerful, destructive, and burned everything in its path. It was always there, whether it was when he was out fighting villains, or yelling at Shouto's mother at home. It was a part of him, just like the cruelty and pain he caused his wife.
Ice, or rather, snow, symbolized his mother. It was gentle, just like her, hiding the world's ugliness beneath pure white flakes. Shouto knew his mother wasn't happy, anyone with half a brain could see that. He had glimpsed one of his parents' incredibly one-sided fights when he was about 3. He could still remember the glow of his father's flames as they devoured his mother's weak ice shield. He'd seen the burn it left on his mother's shoulder the next day. It looked painful, yet his mother still smiled, and told him not to worry about it.
His mother had tried to shield him from the brunt of Endeavor's cruelty, but just as heat melts snow, she too broke. In a single night, she was gone, leaving a scar over his left eye and a gaping hole in his life where she once was.
He quickly learned to shield his heart in ice, grasping desperately to the power he received from his mother. Fire had caused his mother to break, and he was scared to use it for fear of bringing suffering to others like his father did to his family. Scared of feeling the heat on his skin and remembering all the times he'd felt it in Endeavor's training sessions. And so, for a decade, he built a fortress of ice around his heart, and caged his fire deep below the surface, where not even a spark could escape.
"IT'S YOUR POWER, ISN'T IT?!"
Midoriya screamed those words at Todoroki. Midoriya's words brought back memories of his mother's words from so long ago.
That's right…
It's okay… for me to become… who I want to be!
His thoughts were quickly drowned out by the fire washing over his skin and building in the air. The feeling of his father's- no, Shouto's - fire on his skin felt so wrong, yet so right. It was terrifying. It was exhilarating. He felt… complete.
For the first time in a very, very long time, Shouto grinned. For just a few moments, it was just him and Midoriya. For just a few moments, he completely forgot about Endeavor. For just a few moments, he wasn't Endeavor's son, Todoroki, the perfect weapon, or even his mother's son. For once, he was just him, just Shouto, and gods, was that a freeing thought.