Undersocialized kittens?

So i adopted 2 kittens, and i got the second one because the people at the shelter recommend i get a guide kitty in order for the undersocialized kitten to settle in better and learn social skills from the older kitten. Its way past the point of giving the kitten time to get used to the house, I've had him for 3 months.

However he doesnt seem to be improving at all. He doesnt show interest in toys, won't make eye contact, and runs away whenever you look in his direction. The other kitten is very social and likes playing, follows me around all day.

I dont know what to do at this point to get him to trust me or play, or just exist comfortably. He still cries a lot and i don't understand because he doesn't lack food or water, he has a safe space in the house where he naps, but all his body language indicates he's scared whenever you try to approach him. Even just when i put his food bowl down after refilling he backs up.

He doesn't scratch or bite but he cries a lot. Has anyone ever dealt with a kitten like this? Im really trying to figure out how to help him but everything i read or watch tells me he needs to learn to play or respond positively to treats, which he won't do.