You didn't say if the keet was on her shoulder when she wouldn't let someone come towards her. They bite when they get hormonal or if they just don't want the attention your giving. They sometimes bite if they are not feeling well. They bite when protecting their cage mate or nest of if they are fearful. sometimes it's because something has traumatized him. If you determine that he is healthy then try changing his toys and perches around or moving his cage. For playtime,remove the bird from the room where his cage is and try handling him in a safe place which he's not familiar with at all. If he was previously tame and has just begun the biting perhaps he has been left alone to long and has reverted in his training. Good Luck

Cookie and Sweetie