Notorious but better-than-it-sounds [[SciFi science fiction]] novel by the equally notorious [[Creator/JackChalker Jack L. Chalker]]. It posits a world in which TimeTravel to or from the past is possible by [[MentalTimeTravel "leaping"]] into the body of a person of that time. There is a catch: spend too much time in the past, and you'll 'trip' and be stuck as that person permanently, even if you return to the present.
When the hero's first leap into the past uncovers a full-fledged war for control of the future, things go from bad to worse very, very quickly.
Predates QuantumLeap by more than a decade.
* AuthorAppeal: It is Chalker, after all.
* BrotherSisterIncest: Guess what happens when you grow up on a desert island with no one but your parents and siblings for company?
* ButterflyEffect: Subverted: you have to kill someone really important before they'd accomplished their life's work to significantly affect the outcome of history. If you killed someone in the Middle Ages who was an ancestor of, say, Teddy Roosevelt, there'd still be enough genes in the pool for someone to give birth to Teddy Roosevelt hundreds of years later. History is like a big river and it "flows" around small impediments.
* DifferentForGirls: Specifically averted by TheMindIsAPlaythingOfTheBody.
* TheDragon: Eric Benoni.
* ForWantOfANail: The protagonist turns out to be the nail. [[spoiler: he's the mother of the BigBad]] And it's implied that other time travel experiments also "failed" because their subjects were forcibly recruited into the time war by future time travelers.
* EvenBadMenLoveTheirMamas: Eric again
* GenderBender: Several, as you don't get to pick your target when you travel to the past.
* InSpiteOfANail: Played with: Killing Karl Marx before he publishes ''Das Kapital'' has a big effect on the time stream, killing him after not so much, and killing him shortly before he would have died anyway has hardly any affect at all.
* NoOntologicalInertia: Subverted. "nightsiding" people (cutting them off from their prior selves) does not make them disappear or eliminate what they have done, but it does make them vulnerable to OntologicalInertia
* OntologicalInertia: played with as well. Time does its level best to shunt time jumpers into insignificant people who can't or won't affect the timestream. And if you get nightsided, watch out, because time does not like loose ends.
* RetGone: The goal of the war is to do this to the enemy.
* RippleEffectProofMemory: Subverted: You lose some of yourself (and gain some of the personality of your new host) every time you 'trip'. And if you spend too much time in the host's era afterwards you'll be totally assimilated. The heroes use an entire supercomputer just to keep track of the temporal logistics to prevent this from happening to their troops, and it means some people can't go on some missions because they'll exceed their exposure time.
* DisappearedDad: The driving force behind the Dragon.
* PlaceBeyondTime: Not really, but the heroes' base is in the early Cenozoic, far enough back so plate tectonics will destroy all of the evidence.
* SanDimasTime: The "edge" in the future is always moving. [[spoiler: The entire plot turns out to be a huge scheme to extend the edge long enough for people in the future to disarm the bombs their enemies had set as a booby trap. The huge, convoluted stable time loop was merely a distraction to give the people at the edge time to work.]]
* ScrewYourself: And have lots of children doing it.
* SelfMadeOrphan: Combined with TrulySingleParent and EvenBadMenLoveTheirMamas in a way that only a TimeyWimeyBall makes possible.
* StableTimeLoop: Used to "nightside" people by cutting them off from their prior selves.
* TemporalParadox: Several.
* TimeyWimeyBall: And how.
** [[Justified]]. The rules of time travel ''appear'' to change around, but that's only because it's so poorly understood that nobody knows what the rules actually are. Combine this with improvements to the process and the technology, and things look especially inconsistent.
* TimePolice: The hero is forcibly recruited.
* TrulySingleParent: Using a Gender Bender and a StableTimeLoop instead of cloning, but still...
* UnfortunateNames: Ron Moosic, the Hero.
* TheWarOfEarthlyAggression: The time war proves to be a second front.
* WordOfGod: Chalker claimed that he wrote this story in an attempt to address the questions raised--[[TakeThat but not answered]] -- by Creator/RobertAHeinlein's ''Literature/AllYouZombies''.
* YouAlreadyChangedThePast: Used, averted, and subverted as the hero experiences several time loops from various perspectives. Shows up initially when the protagonist learns that ''he'' is from the past and the real leading edge of time is hundreds of years in ''his'' future.