Awesome, knowing there's triggers already. That just makes it even more interesting. Be ready to have a big ass "wtf" conversation with your friend after all this is done Allen. And don't expect any niceness for the condemnation just because you're too weak to take revenge for what was done to you. Besides, he's not hurting his brother; he's destroying his replacement. Though technically he's not really done much to Shouto here, asides from been pissy at him a few times. Without their father here, Dabi's animosity towards his brother's more muted. There's no real burning "reason" without Endeavor, asides from general discomfort.

Trust him, if he sees there's a way to ping Allen using his story, he's going to try to ping as many buttons as possible. Cause he's an insane sadist who likes seeing people suffer. (Probably a reason he's a beast...)

Sounds about right! Talk talk no jutsu while dodging all the shit like a typical shounen protag. Have fun stabbing Shouto's brother just in time for Shouto to see it! Might even be a dick enough to milk it. (But considering he'll be back to "normal", Dabi might not have much room to talk. Don't expect a thanks, but he'll owe him one later. If he bothers to consider repaying it that is.