Who is Jason Marcus from The Age of Wire and String and what is their importance?

Jason Marcus, also called Jase, is the author's brother. This fact emerges only gradually and obliquely through the course of the book. It also slowly becomes apparent that something happened to Jason. The initial clue given is that Jason is no longer present. Toward the end of the book, the author states that Jason died, although he gives no information about how or when this happened. Only in the most indirect ways, when the author alludes to guilt or blame concerning the death of family members, is it possible to infer that unhappy conditions at home might have contributed to Jason's death. This is simply a guess on the part of the reader, however, because so much of the language in the book is symbolic and inaccessible on a rational level.