...(im trying to remember about-about if they already knew eachother or not, so im just-gonna say they do because, you know-)
".. Yeah, it's-It's me. Sorry for bugging you, I just was walking by and noticed the fire."
Yes, they do. Bakugou was legit dating Kaz for a long time. Kaz just sort of appeared out of nowhere, Bakugou clearly liked showing him off, and no one really knew where he came from or anything like that, Todoroki didn't interact with him much since-y'know-he's with the Deku squad.
"Mph-don't worry about it-I'll be gone soon and then it'll stop."