Psion follows the traditions of science fiction. Its underpinnings involve interstellar travel, the fuel for the engines that allow such travel, various exotic nonterrestrial locales, psionic powers and their uses, and aliens whose DNA makes human-alien halfbreeds possible. The basic plot is also pure space opera — a bad guy threatens life as we know it and the underdog hero, after much physical suffering, prevails. In this, Psion resembles the Star Wars movies as well as various novels by Robert Heinlein, especially his juveniles. What sets Psion apart from the usual space opera is Vinge's attention to characterization. An inward looking character such as Cat is unusual in the plot-driven world of science fiction. Vinge lets the reader know how Cat's past life affects his decisions and his outlook. He is at heart a street rat trying to survive and to impress the woman he thinks...