Pilot X, by Tom Merritt
The Alendans are the only race that has truly mastered time travel. Pilot X is happy that he gets to pilot one of the Alendan time traveling ships, and is particularly happy with the artificial intelligence assigned on that ship. However, one of the most senior ambassadors has asked Pilot X to become Ambassador X (Alendans use a title and single name, those with no position are simply called Citizen [given name]) and to try to negotiate a peace between two other races. These are the Progons, a race of machines who can communicate with the past, and Sensaurians, a kind of jelly-like entity able to communicate within their hive mind to any time in the past or future.
Ambassador X is told that these two races are determined to destroy a fixed time point, which would create a disturbance through the entire universe. What follows is a pleasantly bizarre series of time traveling events to serve the goal of stopping the two races before they can act. Merritt manages some mind boggling time sequences, such as Pilot X landing on a planet in a primitive point in its development to train with a retired Ambassador who lives like a hermit. While his companion waits in the ship X is detained for three cycles of twelve years, each new cycle introducing another instance of himself, until he can fully absorb the languages and skills he’ll need for his mission. He finally goes back to his companion in what seems like a short time for her but in which he’s aged a dozen years.
Merritt’s time manipulations generally work well (despite the paradoxes) as X travels through time, sometimes returning back to nearly the same time, to try to save the universe. Sometimes the shifts are a bit hard to follow. Meanwhile, as he travels, he begins falling in love with the ship’s AI, which is slowly developing a sense of humor. He also learns that he’s actually been drawn into a sinister conspiracy with the expectation that what he will really accomplish is the opposite of what he thought he was doing.
It’s a universe of interesting and unique aliens written with humor and quite a bit of action. The most human-like race, the Alendans, have a complex culture, including a group that refuses to travel through time in order to keep watch on the universe in its natural sequence of events.
The book as a whole is a fun read with a bitter-sweet ending which, appropriately, is hinted at in the opening of the book. It’s the most “Dr. Who-ish” book I’ve run into without actually involving The Doctor.