A friend’s ex BF had a female African Grey which was extremely jealous of my friend. The bird would “be nice” when the BF was in the room, but if my friend walked by the bird when he wasn’t around, the bird would reach out, hiss and bite the crap out of my friend.
I’ve heard that birds often tend to be “one owner” pets and can be very territorial and possessive of their owners. My cockatiel was the same way about me.
I can tell you that 4 of mine are territorial and jealous in one way or another. The other is an attention whore and will go to anyone.
Two of my birds really dislike leaving their cage. They will, but only with the right person. The macaw will not allow me to touch him, but he will readily condescend to allow me to clean his cage and refill water and food bowls and give him treats. He half-heartedly lunges at me to remind me not to take any liberties with his person.
My gray allows anyone to pick her up and give treats, but only I can scratch her. Same with the Amazon, but she won’t allow my kid anywhere near her cage.
Birds are funny that way - very suspicious.