Complex sentence: The Losers are the group of misfit children who are united by their unhappy lives, their misery and torment from being the victims of bullying at the hands of Henry Bowers and their eventual struggle to overcome It.
Split into simpler sentences: The Losers are the group of misfit children who are united by their unhappy lives. They share the same misery and torment from being the victims of bullying at the hands of Henry Bower and band together as they struggle to overcome It.