Warning: This post contains spoilers for the sixth season of Game of Thrones.
Fan theories are not a new thing — remember that trippy reading of Ferris Bueller's Day Off? — but Game of Thrones seems to be the first instance where such speculation actually ends up proving to be canonical.
For a long time now, fans of the show have wondered about the parentage of Jon Snow. The most prevalent theory held that he was likely the child of Rhaegar Targaryen and certainly Lyanna Stark — the sister of Ned, whom many thought was Snow's illegitimate father.
Sunday night's sixth season finale virtually confirmed that, yes, R+L=J, as the theory was dubbed. The episode did not explicitly confirm that Targaryen was the father, but critics seem to feel like it's not an unsafe assumption.