Game of Thrones, like so many literary adaptations of fantasy that came before it, is maximalist by design. The dense lore created by George R. R. Martin covers hundreds of years of fictional history and an imagined map that spans two continents and dozens of kingdoms. There are so many family names, crests, house mottos, longstanding political rivalries, and accounts of battles to keep track of that Martin has spent much of the last decade publishing supplemental texts — like The World of Ice and Fire — instead of finishing The Winds of Winter. One of those books, the Targaryen family history called Fire & Blood, became source material for the HBO prequel House of the Dragon.