First we have Laroki, a 12 year old alien who came to Earth with her family to visit. She's a very nice girl who has an alien equivalent of ASD. She and her family are innocent aliens.
Then we have April, the earthling that Laroki made friends with. She has ASD, and is very similar to Laroki, which is why they are such good friends.
Then we have Veronica, who is supposed to be a villainous parody of Dib Membrane. She's a paranormal obsessed kid who thinks Laroki and her family are alien invaders, when they really aren't.