I feel like-yours is pretty good I mean Todoroki's-difficult. Like I have a really hard time writing him, and I'm literally writing a fanfic where he's one of the POV characters. I think like-the main thing to remember is he's a weird mix of eloquence(just like how he speaks, he doesn't really use like contractions or like informal terms), HARDCORE bluntness like he doesn't understand social cues so he just kinda says whatever, and um yeah he's definitely really kind but it's like-almost like this oblivious sort of kindness. It's like there's no...choice there he just kinda does that cuz-that's what he's supposed to do, right?
And yes Kaz is who you're thinking of. They're just like-they're honestly really good for each other. Daddy issues and firepower, man...