What to do?

So I'm fostering a stray mama (Duchess) and her kittens (Batman, Prada, and Pepsi). Batman and Prada are socially well developed. They even let us pet their little bellies. I'm just worried about Pepsi. He's the only one that's scared of humans. He flinches when we try to pet him. When he walks over my feet, he shakes his paws quickly in disgust. I've fed him, spent time with him, played with him, etc. I don't know what else to do. Any suggestions?

Also, Batman and Prada can eat on their own. Batman wakes up, eats, and goes back to sleep But Pepsi only eats after observing his mama eating. Please help.

They're about 8 weeks old, and I want to make sure Pepsi has had some progress socially before giving him a new caring home.

My vet told me to use a method called scoop and cuddle. You pick up the kitten and coo and talk to the kitten like a baby. Give lots of rubs when you hold him and do it lots a times everyday. When I visited a shelter for abused cats I saw them doing it. They would snuggle the cat with a soft blanket and hold them more. The key is not to let the cat go immediately, not in a mean way but a firm way. You keep doing it and then for longer periods. They and my vet(who is a cat lover)swear by it.