On the contrary, with proper training, it's possible to socialize him with other people. This Tuesday, I went over to someones house, half expecting to have a very nippy green cheek conure that could not be handled shoved onto me because the current owner *could not* handle her. Daughter bought the bird for her mother as her mother had always had tiels in the past, but the bird, Winston, loved the daughter. Daughter goes off to college, mom is stuck with a bird that bites and nips. It was kind of a last straw once Winston reached out and bit her lip. After that, mom lost all trust in Winston and she was confined to the cage. Mom, sad and heart broken, reached out to someone else, asking if she might know someone wanting a green cheek conure... and word got to me. My phone number got back to her, she called me, and we met up.
I go over and yes, I see a bird that enjoys nibbling, and hard, but not a bad bird. The mother couldn't get the bird out of the cage, but I, a complete stranger, was able to not only get Winston out of the cage, but had her stepping up a little between my hands, had her turn in a circle a few times, and allowed this strange bird, known for nipping, get up on my shoulder. The mother told me that once she gets up there, you can't get her down! She'll bite and avoid the hand! And then people end up chasing her around... I managed to get Winston to step off my shoulder just fine!
Winston wasn't obeying commands because she doesn't know any, but she is *so* highly food motivated that it would be so easy to teach her. When I left, Winston's owner/mom was excited to start working with her, and perhaps finally getting that bond she's wanted with the bird for so long!
On a side note: Yes, Winston did bite me, and she bit me good! However, this was because she had a toe stuck in her leg band and I didn't put her in a tight grip in my left hand so she still had movement of her head - which allowed her to bite my right thumb. I've gotten used to such bigger bites from other birds that her bites didn't phase me in the least!
I don't believe that once a bird becomes "bad" that they are stuck that way! They just need guidance!
Lauren, AJ's behavior probably became this way because your friend reacted negatively and AJ may have found it exciting enough (good or bad) that he has to repeat *his* behavior.
I must ask, when people come over, is AJ in his cage and he's let out after the people come in? Or is he already out when they come over? Can he see when they come inside the house or is he hidden away from the front door?
I would suggest to start clicker training him or using positive reinforcement training. Teach AJ to target and to station and reward him for good behavior. Once he has those behaviors down, you might then to try and target AJ to sitting near or on a strangers hand. Please keep in mind, the stranger/friend will need to remain calm and relatively still during this or else it will make training AJ more difficult.
The best way to break him of the habit of going after other people is to socialize him with a variety of new people. At first, it can be him being near them, maybe the new people giving him his *favorite* treat or toys and speaking to him but no physical interaction... and then this leading up to him stepping onto their hand or arm for a special treat. The more positive interactions he has with people he doesn't know, the more he'll enjoy getting to know new people.
If he's up on the shoulder, can you distract him with foot toys, treats or perhaps a birdy necklace (worn by human) to keep him from biting on flesh? If not, his shoulder privileges may need to be taken away.