Bill Casey is a kind of antagonist and is the one that killed everyone that Al was near to.
Also, he hated Puacar Wami, because one day, his sister was kidnapped and Puacar made him a kind of deal, Kill another girl (Rettie) and the sister stays alive.
It turned out the girl was the sister (Not Rettie), but Bill did not kill her so the sister died anyway.
He lost a finger at the end of the second book, and Al Kept it to remember Bill.
He has a sister and a brother. The Brother is still alive, and seeing as he lived far away from the city, the brother did not forget, unlike Bill.
He has the other Puacar Wami doll.