Of course, seeing as Shoto and Dabi are both male, this route does not apply to them. This is just me being a nerd. Now, let’s delve into the ethical route.
Even if Shoto and Dabi have not been raised together, that doesn’t change the fact that they both share the exact same parents. In the eyes of the world, it doesn’t matter what environment they were raised in; they are blood related siblings. I love BL as much as the next girl, but some ships are just strange to thing about and downright seen with disgust. Just imagine; if two blood related siblings in real life were living under the same roof, could you rest easy if you know that they were in a romantic relationship? Even if their parents were in the house, there are plenty of opportunities for the two to be intimate with the excuse of being siblings. While this is disturbing enough if both individuals are consenting to the relationship, it would make things even worse if one sibling is one-sidedly forcing the other to be intimate. The forced sibling would be bound by the shackles known as living under the same roof, unable to move out until they reach a certain age, and the offending sibling could use their sibling ties as an excuse to say that their sibling was just being irrational, or that it was a sibling fight.
All in all, while I understand your want to write fan fiction about the ships you love, some ships need to sink. I’m sure that you’re not a bad person at heart, and that maybe you didn’t think things through enough. Please take my words into consideration as you think about your next steps forward. ❤️❤️❤️