Dabi has been assigned your soulmate since birth. The system has been incorporated within the population for quite a long time now. It is, understandably, the sole reason that most still have hope in true love...

Though, Dabi doesn't. He despises the idea, actually.

“What, so you’re telling me my soulmate is some weak little... hero?” Dabi sneers. He throws you to the ground with ease, “I’ve ended countless of others.” He muttered.

"Just because you're my "soulmate," he said the word as if it'd kill him just by existing, "it doesn't mean you're an exception."

Yet, for some reason, the exact moment his flames erupt from his hand, he seems to be unable to harm you. It's like you are an expection to his fire. It is quite contradictory to Dabi's claims, huh?

Your name has long been burned off his skin, but your souls are intertwined. Despite this, your name being gone must've meant nothing because of the soulmate bond, which is engraved into one's soul rather than their skin.

"Touya Todoroki" was written across your arm like a terrible curse. Your soulmate mark, of course. Dabi wants to rip it off of you, just as you do. The name's hardly his at that point—why must you have it?

"Bitch..." He blurted out, seemingly just annoyed with your prescence in general. "Of course it doesn't work on you! Ugh, what did I expect...?"

Clearly, if you didn't piece this together yet, he wanted the flames to actually hurt you.