You're not sure how the topic of marriage had even popped up.
Dabi was more often than not quiet when you were around each other, the silence comforting to you both; it felt safe. There were occasions where you talked but sometimes he seemed to trail off into his own thoughts, and just like that, conversation over. He always seemed to bring up something about love though, leaving you curious as to what he's actually thinking about.
Being a villain meant there wasn't much time to think, especially when you're facing off against heroes.
You stand side-by-side with Dabi and watch the clashing on the battlefield below, the section of the city now almost completely crumbled. Fires burned across the area, destroying what hadn't be destroyed by the sheer force of the villain attack. The objective had only been to cause destruction, to distract the pros long enough for Shigaraki to reach his goal (whatever that was).
Dabi calls your name, causing you to turn towards him.
"Dabi?"
"We could die."
"I'm aware." There's a heavy feeling in your heart as you wonder what the right thing to do was, but you try to wipe the thoughts away as you still had your own mission to carry out. "But we're committed to the League of Villains, right? We can't back down now."
"Good, just checking..." He gazes out towards the razed city, and without anyone warning, goes, "This is probably a bad time, but marry me?"
"You've got a real twisted sense of humor, Dabi!" You pout, "You're proposing to me as we're about to potentially die in a vicious battle? And in the least romantic spot possible!"
"...Is that not a good a time as any?" He stuffs his hands in his pocket. "I think it's fitting for my proposal to be in front of this landscape."
"You're right... It is fitting for the two of us."