WARNING: The following contains spoilers for My Hero Academia Chapter #301, “The Wrong Way To Put Out A Fire, Part 1,” by Kohei Horikoshi, Caleb Cook and John Hunt, available now in English from Viz Media.
Chapter #301 “The Wrong Way To Put Out A Fire, Part 1” of My Hero Academia showcases many important backstories and themes that, until now, have only been briefly talked about in the series. As Endeavor reflects on his past treatment of Toya, now known as Dabi, Rei comes to finally confront her emotionally broken husband.
To everyone’s surprise, she is not there to comfort Endeavor, but rather to make sure he understands what he has created. It all began with Endeavor’s overwhelming desire to surpass All Might as the number one Pro Hero, deciding to commit to a Quirk marriage in order to satisfy his desire. The only problem with that plan is that Quirk marriages are considered taboo in the hero world, and the Todoroki family is a good (or bad) example of why that is.
First off, Quirk marriages are used to sustain and carry family hierarchies in My Hero Academia's society. Rei’s family used to be a prestigious one, and they decided to accept Endeavor’s proposal to ensure the family name could live on. It’s unclear what happened to the Himura family, but seeing as Rei was the only daughter, their lineage was coming close to an end. Marrying Rei to Endeavor without her full consent shows how the "weaker" members of society are taken advantage of for the benefit of the stronger heroes. Endeavor may have shown true affection towards her once or twice, but that didn’t change Rei’s feelings.
Quirk matchups like this -- designed to produce strong offspring -- are also very unpredictable. In Toya’s case, Endeavor wanted someone who could surpass his own flame capabilities, which Toya did, but the fault in his inheritance came from his mother’s physical attributes. Toya’s body was not able to withstand the heat from his own flames, leaving his body constantly burned.
Toya did inherit the ability to survive in freezing temperatures, though, which comes into play when he has to face-off against Shoto. The unpredictability alone put Toya in an unfortunate spot, and in the end, made Endeavor give up on turning him into a hero. Toya was under the impression that this was his destiny but that was never really his father's goal; rather, it was Endeavor’s own pride forced upon him.
Not only is Endeavor's ideology toxic for his family’s overall psyche, but the idea of creating life for the purpose of Quirk perfection takes a toll in other ways. Rei was the one who was treated as a Quirk-making machine until the ideal results were yielded. This is probably one of the bigger reasons why Quirk marriages are taboo in hero society. It seems like one person is always getting taken advantage of, and in this case, that’s Rei. In the beginning, she was doing it for her family, but she quickly became the only true parent figure for Natsu, Fuyumi and Toya after Shoto started receiving Endeavor’s full attention.
In situations like this, the other children are forever seen as failures, and that makes them feel inferior to their kin since they don’t possess the desired Quirk combination. Shoto was very distant from his siblings early on in the series because he knew he was Endeavor’s prized child, which is what started him on his path towards rebelling against Endeavor. Dabi is the only one who pokes fun at this when they first meet, but the other sibling learned from Toya's treatment, and were more accepting of Shoto.
My Hero Academia's Quirk marriages seem like a good idea on paper, but when you get to their root, it’s a gamble for everyone. The parents will always be hoping for their ideal candidate while neglecting their other children. And the children will always feel like they were only born to serve a purpose, and not out of love. There is also the worrying idea that such a union could actually make the most powerful being in the world, but the probability is too unpredictable at the moment -- which is actually more of a relief. After all, if it wasn't, All For One would have capitalized on that idea already, making the taboo even worse.