Ok, we all notice that Petrie is the only one of the Gang of Seven that lacks a father figure. Heck, all of the Gang of Seven, minus Petrie, and, er, Spike, have their fathers around still.
A thought just occurred to me that maybe Petrie is, well, a Mama's boy. I know that sounds funny, but could it be true?
If Pterano were to come back, could Petrie get a spine? I just wanna see Petrie get a father figure in his life SOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOO badly!
Still, I think if Petrie had a father, he'd be braver and maybe be less, well, strange.
Maybe his whole imaginary friend and other thing habits are because he doesn't have a father and it's hurting him inside. You could see how much he admires Pterano, and, though we never saw him talk of him before, I'll bet Petrie had and had known his uncle for a good amount of time (er, before Pterano's banishment). I think Petrie sort of saw Pterano as a sort of long-lost father, even if Pterano was actually his mother's brother, I think Petrie sort of viewed him, in a way, as a replacement for a dad. It would explain why Petrie kept defending him despite all the evidence against Pterano. Petrie didn't want to think ill of the man he believed could be like a father to him. Petrie would probably come to help Pterano get the SOCF himself had Pterano not done the Ducky kidnapping thing.
No, Petrie wouldn't have meant ill, but his love for his uncle may have blinded him to what his uncle was up to. He acts aggressive for one of the few times in the franchise when his uncle is criticized.