Martin's Dunk and Egg novellas are set in Westeros eighty-nine years before Game of Thrones begins, and they follow the adventures of the Hedge Knight Dunk and his dedicated squire, Egg.
Martin has published three Dunk and Egg novellas so far, and all three were fantastic. Although they are lighter in tone than the rest of Game of Thrones, the stories feel like a natural addition to Martin's Westeros-canon. One primary reason for the novellas' organic feeling is the success of its two lead characters.
Dunk is a self-conscience yet imposing knight, and Egg is his young, big-mouthed squire. Both characters are immediately relatable and likable, and both went on to become Westerosi legends. Egg - who's full name is Aegon Targaryen the fifth - ends up becoming King of the Seven Kingdoms, and his best friend Dunk becomes his Lord Commander of the King's Guard. Recognize the name Ser Duncan the Tall? That's because he is mentioned in Game of Thrones as being one of the greatest knights of all time.
Though these two friends went on to become incredibly important figures, George R.R. Martin's first three novellas have followed Dunk and Egg during their youth. Martin has revealed that he has as many as twelve Dunk and Egg novellas planned, and that the series will trace their entire lives. Considering Martin is a little busy with The Winds of Winter and A Dream of Spring, a television series would be a great way to tell the adventures of Dunk and Egg.