"A ghost's function? To exist, I guess? Apart from that I think the answer is different for every ghost. A lot of ghosts just want to be left alone. Some other of the others I know want to take over the world or hunt all the greatest trophies or be a rock star that everyone loves."

Danny stops and thinks. This wasn't really something he had ever sat down and worked out before. "Me... I guess its to protect?"

He frowns. "I don't really know why humans are so afraid. I mean, sure, sometimes ghosts attack and their abilities can be scary. But all the humans at home were scared of ghosts a long time before real ghosts started showing up.