>Warning there are manga spoilers ahead<
Ok so I just thought of this while doing homework.
Dabi is said to be Touya Todoroki.
No one knows Dabi's age.
Touya was the eldest sibling.
Fuyumi Todoroki, the second eldest sibling and only daughter is 23 years old.
Dabi looks as if he's in his 20s
Touya is guessed to be only a few years older than Fuyumi.
You see where I'm going with this right?
And Dabi without scars always looked an awful lot like young Enji. (Endeavor)
The similarity is uncanny.