Lyssa Greenfield is almost constantly at war with her brother. Cracked ribs, melted computer disks, concussions and broken noses have come from their constant fighting. Lyssa is a straight-A student and is good with machinery: it is she who attempts the fix of the engine. She supplies wit and loyalty to her fellow castaways. In the middle of book two and all of book three, Lyssa shows that she actually starts to love her brother; 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 Lyssa and her brother reside in Huntington, New York. It is also said earlier in the book that Lyssa and Will are brother and sister. Lyssa has dirty blonde hair. She is 12 years old.