When Game of Thrones debuted in 2011, it quickly earned a reputation as one of television’s most ambitious and influential dramas. Among its sprawling cast of houses, the Targaryens loomed especially large — a once-exiled royal family that had ruled Westeros for nearly three centuries before the events of the series.

Cersei chose violence. Rhaenyra commandeered dragons. But the protagonist of HBO's new " Game of Thrones " spinoff, "A Knight of the Seven Kingdoms"?

We enter this epoch in Westerosi history via a commoner named Dunk (played by Peter Claffey, "Bad Sisters"), the young, hulking squire to a hedge knight named Ser Arlan of Pennytree (Danny Webb, "Penn...