I'm not exactly looking for an antonym, however I am searching for a general term which refers to that which the surrogate stands in for. For clarity, I am using the term surrogate to mean to "put in another's place, substitute."
The best I can come up with is "original," as in: "the surrogate comes to occupy the position of the original." The issue with "original," "genuine," "real," and "true," is that it implies a lack of originality, reality, truth, or a genuine-nature of the surrogate.
Is there a word that works better in this instance?
Any help would be greatly appreciated.