Really quick Danny Phantom theory I just thought of
So a lot of people think, “how does no one know Danny Phantom and Danny Fenton are the same person?? They look and act exactly the same!!” It was really obvious to me as a child, but as I grew up, I realized that a person with the ability to turn into a ghost was a really unique concept. I mean, how exactly would people think of it if they hadn’t known about the portal story? So, that made me realize something.
What if Jack and Maddie Fenton were aware that Danny Phantom looked just like their son? They were aware, but they had no way of knowing that anyone could actually transform into ghosts at will, so it had never occurred to them that the ghost was actually their super-powered son.
What if they thought that this ghost was taunting them, taking this form to imply that their son was going to die?
I can see why they’d hate that ghost in particular.