Charon is the ghost of a cursed male Gardevoir, a vengeful and evil spirit. It's obvious though from the wound on its chest that it must have died horribly and painfully. So it's really no wonder it would be a tormented soul in the first place...
I actually have Charon in my party on VDex http://vdexproject.net/user.php?user=5333
I originally made the sprite as part of a competition where users could submit a special sprite and get it as their Pokemon in their party. It was only a matter of time before Charon went from being a sprite though to me actually drawing him :3