the most common theory is that dabi suffers from burn scar contractures, to the point where his range of motion is severely inhibited.
he had no access to safe healthcare at the time of injury, so the best way to alleviate some of the tightness was to make cuts into his own skin.
the most obvious hint of this: the vertical line down his chin.
it’s also possible that he experienced issues eating, drinking, and talking. he “cheslea grinned” himself, making incisions near the buccinator and risorius muscles so that his mouth could open again. unfortunately, his impromptu surgery was too radical. now, he needs medical staples to keep his mouth shut.
the two (possibly four) pieces of metal that are closest to his mouth’s opening are piercings that look like staples. if you squint, you’ll see a thin metal bar here. that’s a piercing clasp.
but the others seem to be actual staples that connect his top and bottom lips.
we haven’t seen much of dabi’s body, but it’s safe to assume he has staples holding skin together in other places.
he also has modifications that serve no apparent purpose, such as his nose and ears.
my guess is that dabi’s scars were causing him a lot of problems, but the incisions caused even more problems. he can barely express emotion (such as screaming at endeavor) without his staples tugging at his skin and drawing blood.
i bet the staples and piercings match each other for a reason. i bet he has the additional, functionless adornments for a reason.
dabi is a man who has been falling apart for years.
so he’s taking his weakness and personalizing it. he’s expressing himself and intimidating everyone that sees him.
upgrading to gold staples just screams revival and confidence to me.
Solfege Navigator 