Warning! Spoilers ahead for My Hero Academia chapter 350!
Dabi just revealed to his younger brother Shoto Todoroki how he plans to seek vengeance against their father Endeavor in My Hero Academia. Although his plan is wonderfully brutal, it accidentally exposes how much better the anticipation for the fight between Dabi and Shoto could have been. Up until now mangaka Kohei Horikoshi has created a wholly different impression of the context of the brothers' fight.
Although Dabi's troubles first began when Endeavor cast him aside for Shoto, Horikoshi made it abundantly clear that Dabi's desperation was always directed at Endeavor. Dabi might have resented Shoto for stealing Endeavor away, but everything Dabi did as a child was to catch Endeavor's attention. He accidentally burned himself alive, not to one-up Shoto, but to prove to Endeavor that his flames were strong enough and that he could control them. As a result, fans have always looked more forward to Dabi's inevitable confrontation with Endeavor more than with Shoto. This isn't to say that fans never cared because the altercation did promise to be quite the emotional rollercoaster. But the brotherly battle always felt like something that just had to happen first because it was the natural precursor to the big fight between father and son.
It was therefore quite exhilarating when My Hero Academia created the false impression that Endeavor, Shoto and Dabi would go all-out in a two-on-one Todoroki family brawl. So, when Dabi was later paired off with Shoto alone while Endeavor faced off against All For One, it was disappointing but understandable. But chapter 350 reveals that defeating Shoto is a major part of Dabi's plan to get back at Endeavor. For the vast majority of the chapter, Dabi shares what actually happened to him after he ostensibly burned alive in his desperate attempt to catch his father's attention. Reliving these memories understandably works Dabi into a frenzy, and as he prepares to attack, the villain announces that he will burn everything Endeavor holds near and dear.
This revelation shows what could have been. Dabi's plan wasn't just to tear Endeavor down as originally believed, but to destroy the things he loves most. And since Shoto was the offspring Endeavor always wanted because of his Half-Cold Half-Hot quirk, that means that Shoto should have always been one of Dabi's main targets. But past events, unfortunately, don't match this assessment. When Shoto, Endeavor and Dabi first meet in the initial charge, Dabi completely ignores his brother. All he cares about is mocking their father and throwing quips at him whenever he can. Something similar transpires when he is later paired off with Shoto. All Dabi can talk about is Endeavor and how much he is using Shoto. This doesn't sound like a villain whose main priority is to burn down everything Endeavor holds near and dear to him. Dabi even refers to himself as Shoto's big brother and, because of that, Dabi feels Shoto deserves to hear what happened to him.
Of course, there's the possibility that burning everything that Endeavor cares about was never actually Dabi's big master plan. After all, Dabi has just recounted all of the pain and trauma he endured after burning alive. Reliving these memories could have just worked him into enough of a frenzy to make him want nothing more than to destroy everything. Whether the comment is just the product of Dabi's rage in this given moment or is indicative of what his plan has been all along, it shows what could have been. If mangaka Kohei Horikoshi of My Hero Academia had clarified early on that Dabi's childhood made him want to murder Shoto and his whole family to get back at Endeavor, fans would have anticipated this fight much more than they actually did.