Will Greenfield is at war with his sister, Lyssa, as both have been landed in the hospital in one of their quarrels. He views himself as imperfect, and his sister as the perfect, good-looking kid of the Greenfield family, which makes him resent her. Will ends up with amnesia in the second book and does not remember a thing about the shipwreck or the other castaways except for his sister for a brief part in the book, in which he sabotages Luke, Charla, and Ian's shelter. He is later the castaway that is in a life-threatening situation by an infection from a bullet wound. In the middle of book two and all of book three, Will's sister Lyssa starts to show she does truly love him and would be lost without him; Will finds her in book two and they hug each other, stating, "A small part of Lyssa, standing strangely distant from herself, noted that this was the first time she could ever remember hugging Will." In book two when everyone's hometown and state is revealed, it says Will and his sister reside in Huntington, New York. It is also said earlier in the book that Lyssa and Will were named after two flowers, Sweet William and Sweet Alyssum. He has sandy brownish hair and is slightly husky. Will is 13 years old and possibly turned 14 in Book 3.