Question:  In George R. R. Martin's A song of Ice and Fire series who plays the only viewpoint character to appear in every published book of the series?
Sentence (from "Arya Stark"): She is a prominent point of view character in the novels, with the third most viewpoint chapters overall out of all the characters in the series so far, and is the only viewpoint character to appear in every published book of the series.
Relevant evidence: Yes