ok the responses to my other post about autistic might guy made me want to write a more dedicated one so here you go (thank you @emotionalmoss for your thoughts ദ്ദി(。•̀ ᗜ<)
i think gai and dai were definitely both autistic; gai's coding works so well because of how he's been treated by the village, and that originated with dai. that said, i think both of them have more social awareness than they necessarily let on, and the way they behave/present themselves is very intentional
when you meet gai he seems to be like, completely oblivious to how he comes off. he is weird and offputting and loud and just kind of uncomfortable to be around, and appears to have absolutely zero social awareness of that. but like the reblog in the post linked above said, we see in gai's backstory that gai WAS aware of what people thought of him and his father, and in fact it bothered him quite a bit. dai, however, chooses to ignore the mockery (because he is an adult man and has had a lot more time to develop self confidence) and continue behaving the way he does, even allowing other people to believe he doesn't notice the poor treatment. through this, we know that's exactly what gai has chosen to do in his own adulthood too.
there's just something kind of special to me about gai growing up so ashamed--of himself, of his father, of how everyone treats them, and how his dad reacts to it--and not being able to understand why his dad doesn't try to act... normal, because surely that would make people like them more, and then growing up to realize it doesn't work that way, and he's better off being unabashedly himself. gai LOVES being weird and bizarre and throwing people off, and it's something he exaggerates in himself very purposefully! he chooses to dress and talk and act the way he does because that's just... how he is, and trying to suppress that is impossible and unnecessary. there ARE things he doesn't understand, and social cues he misses, and things he does that he clearly does not see as weird even though others do, but there are also things he 100% understands aren't considered socially "normal" and chooses to do anyway, because he doesn't care what anyone else thinks. and i love that for him
now, do i think it bothers him that people make fun of him? yeah, but that is in part a totally normal reaction, and in part his own unresolved issues (see here for my whole post on that lmao). but he can't NOT be the way he is, so he doesn't try. it's not fair that he's mistreated for who he is inherently, and that would bother ANYONE, but he's made it work for him, and he's done very well! despite his full-out rejection of social norms and conventions, people who know him love and accept him as he is (even if he tends to exasperate them)! so, y'know, there's hope for the rest of us yet i guess