I just had an epiphany about Dan, and I had to share.
So, when Danny’s ghost half gets ripped out of him, some people were probably wondering, “Why the heck is Danny’s ghost half evil? I mean, their explanation was that Plasmius’s evil side overwhelmed him when they merged, but Phantom had to have been evil before that to have even considered doing that to Vlad.
I also remembered that ghosts have an obsession. Skulker with hunting, Walker with rules, Ember with music, Box Ghost with boxes, etc. Many people have said that Danny’s obsession is protecting people, thus why Phantom tries so hard to protect Amity Park.
But unlike ghosts, humans can change their opinions, and also obsessions. As a half-ghost, Danny’s ghostly obsession can change under extreme provocation, like his family and friends being killed and him feeling really guilty.
At the time of separation, Danny’s only wish was to remove his emotions because they were too painful to deal with. His obsession at that point was to lose his humanity, and to remove human emotions/humanity in general.
Which is why Phantom rips out Vlad’s ghost half: to rid him of his humanity and make him a pure ghost of just Plasmius and getting rid of human Vlad. Obviously he failed (though he succeeded in killing Danny’s human half), and when the two ghosts combined, Plasmius’s own obsessions merged with Phantom’s hating humanity.
Thus Dan Phantom was born.
People have probably already figured this out, but I just wanted to share the moment of me figuring it out on my own ^_^