habitor

This is a term that you can use to describe someone with a habit or an addiction.

Oscar: "Hey! Did you hear about Nate?"
Jones: "Yep! He's in the mix on the mellow meth. I'm worried. His girl Mariah is sure no help."
Oscar: "It's only a matter of time before he becomes a habitor and we won't be able to trust him. I can't wait!!!"