In English there is the concept of somebody who is a 'leech', and takes advantage of a second person's resources or generosity, financially or otherwise.
What word or phrase could be used to denote the one who is leeched from?
I don't mind whether there are positive or negative connotations to the word - "sugar daddy" is a good American example but not suitable for my (British / Scottish) context. To me this is a good example because it explicitly implies the ongoing leeching relationship, and is not simply an attribute of the person.
edit: In the specific usage I'm looking for, the provision is given consciously by the second party. Beyond that, I don't mind whether the giving relationship is willing or reluctant, personally (e.g. parent) or impersonally (e.g. bank). The word or phrase must function sensibly in the following sentence: "I am not your _____"