Bill Denborough is the unofficial leader of IT's Losers' Club, and here's why he's the most important member. While Bill is the Losers' Club leader, every member of the group matters.
While this aspect is downplayed in the movie adaptations of IT, Stephen King's book makes it clear that it was more than mere proximity and coincidence that brought these particular people together as children. No less than cosmic forces were at work, most notably a giant turtle that, essentially, vomited up the
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