Re: [MEMORIES]
There's a Ghost Zone. Its full of ghost, millions, maybe billions of them. They don't overrun where the humans are because they have their own Zone, but enough still come and the only stable portals are owned by dad and Danny's family. Though Danny's is the only one documented.
So most ghosts would know the exist. So they made up a name to call them, I guess.
They're not all that different from humans, mentally. It's just...they're one aspect of that person's personality and magnified. Obsessions. Dad said halfas are generally powerful because it's easier to 'evolve' mentally.