A hollow.. Is a soul who cannot cross into the spirit world.. They are led by anger.. hate.. even revenge.. I myself am a hollow, but.. *She scratched her head* Some things led to another and a select few of us were allowed a human form.. I was one of them. Coming with human forms was the return of human emotions, and logic thoughts..  Lower class hollows eat the souls of humans to survive.. They will also eat eachother. The more they eat, the stronger they become, and some may even change forms..