Who is Keasley from Dead Witch Walking and what is their importance?

Keasley lives across the street from the church where Ivy and Rachel live. Rachel fmeets Keasley when she mistakenly believes that his house is the place that Ivy rented for them. Keasley reveals himself to be a witch, and he helps heal Rachel when she is nearly killed by the demon. Keasley refuses payment, but he tells Rachel that in the future, he will need her trust.