If This Did Happen, I Could Imagine Him Eating Demon Flesh (presumably Some That Nezuko Donated), And

if this did happen, I could imagine him eating demon flesh (presumably some that Nezuko donated), and Genya’s eyes permanently change into their demon form, black sclera and yellow iris. this of course would distress Genya, but eventually he would accept it and try to move on, (after a small break from training to recover from the shock of everything.).

meanwhile Sanemi has gotten punished for “attempting” (quotes because he did technically blind Genya, even if it was only temporary) to blind a fellow Demon Slayer and is shoving all his complex emotions away. Then he learns from Shinobu (she’s Genya’s doctor) that Genya has made a full recovery and has regained his vision (she doesn’t mention Genya’s eyes are different now)

Sanemi is initially shocked by what was supposed to be a career ending injury, but knows Genya’s quick recovery has something to do with him eating Demons. But no matter how hard he pushes, Shinobu won’t tell him anything (patient confidentiality) and he can’t ask Gyomei because the stone hashira is pissed at him. He can’t ask Genya himself because neither Genya nor Tanjiro are allowed near Sanemi, (an order that Sanemi suggested ironically.) So Sanemi doesn’t see Genya after this and therefor doesn’t immediately learn how Genya’s eyes have permanently turned to that of a demon. All because of Sanemi, his big brother.

how would Sanemi react if he saw Genya with his demon eyes after he blinded him?

Sanemi trying to blind Genya, as if Genya's mentor isn't literally blind and can keep teaching him

This has been pointed out so so so so many times and yes while it’s fundamentally true that Gyomei could have trained him after this event happened, it’s also more than likely genya would have somehow consumed demon blood as fast as he could to regain his vision! Because while being blind and a demon slayer may work out just fine for Gyomei, Genya isn’t as gifted as him, not with physique, the lung capacity (asthmatic genya my beloved and also what reason else could be literally not be able to breathe correctly??). And not with decades of gaining his bearings and refining all his other senses to be able to fight demons once again.

So in truth, If Sanemi HAD blinded him and Genya hadn’t consumed demon blood and just healed naturally. It probably would have worked in completely rendering Genya useless for the demon slayer corps.

This is all just a big what-if though because Genya still probably would have regained his sight if he ate demons before and we don’t exactly know what characteristics a demon can keep from their human body and what won’t transfer over to their demon body. So a person born blind is probably blind as a demon and uses echo location like a bat to hunt humans but if you were Genya, in this scenario, you’d probably gain your vision back.

Semi related but when Shizu clawed at Genya’s face she was dangerously close to his eyes and I’ve been toying with an au where she actually hits his eyes and Sanemi can’t abandon him then aka which leads to one of my favorite au’s: spoiled Genya of the wind estate. Might become a fic:3