Science-fiction series by Richard C Meredith, about The Multiverse, consisting of At The Narrow Passage; No Brother, No Friend and Vestiges of Time. Eric Mathers is a Timeliner, an employee of an alien species called the Krith, who have developed the ability to "skud" between timelines. Using this ability, the Krith have built a substanstial cross-line empire, and developed technology to duplicate their natural ability. Using skudders and their human contractors, the Krith are trying to stabilize as many Timelines as possible so as to fight off a distant invasion.