Everyone knows that Todoroki is pretty much solely focused on becoming a hero. It’s kinda expected when his father is the number one hero. But what everyone besides Midnight-sensei doesn’t know is that he’s developing a crush on you.
Midnight told him that after a very embarrassing conversation about why he feels himself getting red and losing control of his fire side whenever he thinks about you for too long. She had to explain that he wasn’t loathing you, but instead had a crush on you. And she told him to express himself to you subtly but it seems her instructions were taken by the dense boy incorrectly.
You had gotten a bad flu during winter break and you had to stay in the dorms. So when Aizawa asked anyone wanted to stay in the dorms during winter break to care for you Shoto immediately raised his hand and took up the opportunity. He got a valid excuse to not see his family and he got to show that he cared for you just like Midnight told him too. Win-win.