Note: All Might frustrates me. My Shouto bias toward is strong. If All Might is your favorite, this might not be for you.
He knew once All Might didn't see it, he truly could get away with anything. As long as he kept the bruises in places her clothes would cover. As long as the children understood what was meant to be private. As long as he could make Shouto understand. In the end the boy would understand and so would his mother. Once the Todoroki name stood above all others they would thank him for his hard work.
The first time he slipped it was a slap. She'd begged him. How base. Todorokis never begged. Why was he the only one who could see beyond the now and into the future? So the boy was weak. He wouldn't stay that way. Shouto would be strong. The strongest. She just needed time to grasp the weight of his work.
This was All Might's fault anyway. She could blame him for being so obnoxiously visible and loud and arrogant. He went about punching things and did it with a smile. What a farce. Nothing was ever all the way good. Even things that sparkled had a core of filth. Everything.
Enji sparkled too. He did. His core could be purified by his son's successes. Shouto would shine brighter than them all.
He would burn.
He was ashamed at how long he took to notice. In his defense they were little things. And he was busy. He had problems that overshadowed a youthful rivalry. But still. Still.
The public wrote it off as simple privacy. Why wouldn't the number two hero, Endeavor, want to keep his family sequestered from the every roaming public eye? How completely reasonable! But once Toshinori noticed the details… he couldn't unnotice them.
The mother of Enji's children was a quiet woman. Never seen without her husband. Her eldest three children were rather unremarkable compared to Shouto. The first time Toshinori forced himself to look at the boy - really look - he was horrified.
It didn't take a master detective to find out where the mother had been hidden away. The allegations. The hospital - not as nice as it could've been for a woman of her status. The burn. Logic took Toshinori by the balls. The boy couldn't have burned himself. Even if Enji abused his wife and children, would he be so foolish as to permanently scar the child he groomed for fame?
Of course not.
Why would the mother… oh. Oh.
There was nothing to be done about it, of course. He had his own problems. Big ones. Problems that overshadowed a youthful rivalry.