Help! Little kitty monster

My 8 month old kitten is starting to become aggressive in certain situations. We got him as a 4 week old feral kitten with his brother, but he was  able to get over that and be a normal friendly cat. He grew up in a house with other cats and all was normal for several months. The first time I noticed his aggression was when I brought him to the vet and he lashed out at the tech. I didn't think much of it because I figured the vaccine just hurt. Since then he has been VERY sweet to me and most people entering my apartment where he lives as the only cat. As soon as I bring him home and he is back with the cats he grew up with (who are both people friendly) he turns into a schizophrenic weirdo. When I pick him up he will lick my face nicely and then hiss and try to bite me. He loves the other cats and has tons of fun playing with them so I don't think it is just redirected aggression. When my other family members pick him up he will try to attack them but then later goes and sits on their lap or chirps and rubs against them. Why is he SO sweet when he is the only child but appear to have split personality disorder when he is with his best kitty friends? Have any of you experienced this? It's sad :-(

I have 3 cats that are now adults. They were brought in to my home as 3 week old feral kittens. My daughter adopted one and I kept 3. I have one who is mean for days after his sister comes over to visit. He is even aggressive towards me and he is a big momma's boy. I think it is a territory issue. When he is in his territory he is calm, but when he goes home it is not his territory.  My cats are very sensitive to any changes.