While the world awaited each new volume with lines outside bookstores, Rowling used this time between releases for something beyond writing — she was also silently weaving a network of secondary characters so rich that many fans would come to prefer some of them to the original protagonists. Hogwarts needed to seem not just big, but infinite.
The idea, which became increasingly clear as the saga progressed, was that no character introduced would be decorative — each new face would carry its own motivations, capable of sustaining entire arcs even outside the main focus of the plot. It was a bet on depth over quantity, even as the cast grew with each book.
That was how names like Fred and George Weasley emerged, whose irreverence hid genuine courage revealed only in the final books; Neville Longbottom, introduced as a shy and clumsy character, but whose trajectory would become one of the most silently heroic of the entire saga; Cho Chang, Harry’s first great love interest; and Dolores Umbridge, introduced in 2003 as one of the most hated antagonists in modern pop culture — proof that Rowling knew how to create villains as memorable as her heroes.
By multiplying characters with this depth, the saga ceased to depend only on the central trio to sustain the readers’ interest — Hogwarts, year after year, revealed itself as a universe where any secondary name could, suddenly, become essential.