A Golden Age Science Fiction series by H. Beam Piper. The premise is simple: a highly advanced and sophisticated Human society has exhausted the resources of the three life bearing planets of our solar system and now survives as a parasite on other, less developed timelines including our own. This exploitation is supervised by the Paratime Commission whose enforcement arm is the Paratime Police.
The infinity of timelines is organized into 'Levels', the point of divergence being set some hundred thousand years ago at the point in time when Homo Sapiens, Sapiens abandoned our original home world, Mars, to colonize Earth.
First Level, including the Home timeline, resulted from a successful transition of Martian culture in full to the new world.
Second Level evolved from a less successful colonization effort that resulted in some loss of cultural and technological continuity.
Third Level descends from a near failed colonization effort in which a few shiploads make to Earth but receive no support from Mars and are forced to rebuild from scratch losing all memory of their origins.
Fourth Level, which includes our timeline, developed from a handful of Martian castaways who managed to survive after reverting to stone age levels of technology.
Fifth Level comprises those timelines where colonization either failed totally or was never attempted. Some sectors are peopled with Neanderthal or other varieties of early man, while others have no intelligent life at all.
Levels are in turn divided into geographical and cultural 'Sectors' we, for example, are the 'Europo-American' Sector.
Most of Piper's Paratime stories feature Verkan Vall, Chief's Assistant, i.e. second in command, of the Paratime Police force:
- Police Operation: Verkan is forced to track down and kill and ET animals accidentally let loose on an 'Europo-American' timeline.
- Last Enemy: Verkan goes to the rescue of his ex-wife whose been kicking over anthills on a Second Level timeline.
- Temple Trouble: A Paratime industrial operation under cover of a religious cult is threatened by a new god.
- Time Crime: A huge slaving operation is uncovered on a fourth level timeline.
- Lord Kalvan of Otherwhere: Verkan is faced with deciding the life or death of a paratemporally displaced Pennsylvania cop.
Examples of Tropes
- Advanced Ancient Humans: The Martians who settled or didn't settle Earth in prehistory.
- Alien Non-Interference Clause: The one unbreakable Paratimer law is the Paratime secret MUST be concealed. However they also try to work from within the culture and avoid interference even for moral reasons. For example Paratimer corporations on slave owning timelines must use slave labor even though it is morally repugnant and uneconomical.
- Alternate Universe: The whole premise in a nutshell.
- Alternate Timeline: Millions of them.
- Alternate Techline: The technological level of the many timelines exploited by the Paratimers varies from stone age to space age.
- Ambiguously Brown: This seems to be the dominant skin color on Home Timeline. Verkan is able to 'pass' in the great majority of timeline cultures only resorting to cosmetic treatments in 'Last Enemy' and 'Lord Kalvan of Otherwhere'.
- Cassandra Truth: Part of a Paratime Policeman's job is to make reports of paratimer sightings into this.
- Cultured Badass: Verkan Vall is educated and sophisticated in dozens of cultures - and capable of killing three men in successive duels.
- Battle Couple: Verkan Vall and Hadron Dalla become this in 'Time Crime', thus guaranteeing that this marriage won't fail like their previous one did.
- Casual Time Travel: Paratime transition is so casual that people use it for out-time vacations, or even just to have an evening out somewhen else.
- Everybody Smokes: Like chimneys; cigarettes of cool, cigarettes of glamour; cigarettes of anxiety, cigarettes of boredom to pass the time...
- Expendable Alternate Universe: Home timeline carefully guards the secret of inter-timeline travel and takes advantage of resources from less developed (or completely uninhabited) timelines. The Paratime Police suppress gross exploitation such as inter-timeline slave-trading, but the bottom line is that Homeline's interests come first.
- Fake Memories: Trained 'Psychists' can overwrite a subject's memories but the process is far from fool proof and can be undone - though not quickly or easily.
- Fantastic Caste System: The Paratime Race has a vestigal nobility but the main class division seems to be between 'Citizens', natives of Home Timeline, and 'Proles', imported from Fourth Level timelines as workers.
- Flying Car: Home Timeline doesn't seem to have roads, or even sidewalks, but it has robot flying cabs.
- Handbag of Hurt: Dalla uses her evening bag to demolish an assailant with the drop on Verkan.
- Humanity Came From Space: Mars, specifically, and timelines are categorized based on the level of post-colonization regression.
- I Need a Freaking Drink: Verkan knows the news is bad when he walks into the Chief's office and finds their expert is downing straight rum.
- Infinite Supplies: For Home Timeline thanks to the exploitation of less advanced timelines. The Paratimers are honest with themselves, they are parasites. But principled ones.
- I'm Taking Her Home with Me!: Dalla does this with a beautiful, intelligent 'Prole' girl who is a witness in 'Time Crime' adopting her as her sister.
- Info Dump: Especially noticeable in the earlier stories.
- In Harmony with Nature: The inhabitants of the Dwarma Sector are described as this; lovely people but after a few weeks with them you will be bored silly.
- Interdimensional Travel Device: The Paratime conveyors use the Ghaldron-Hesthor field-generator to jump timelines. They do not change physical position meaning that one must either use conventional transport to get to a conveyor fixed at the site one wishes to arrive at or arrange for transport at the other end. Paratimers in transit note the constantly changing environment outside their dome shaped field. Weakening of the transposition field is a major concern of Paratimers, especially the possible intrusion of dangerous animals or human beings.
- The Masquerade: Paratimers go to considerable lengths to conceal their out-time origins and fit into the local culture. Smart Parasites never let their victims know they exist.
- Must Have Coffee: The Paratime Police seem to run on caffeine and nicotine.
- Naming Conventions: On Home Timeline the family name comes first and the personal name second.
- One-Man Industrial Revolution: Corporal Calvin Morrison, aka Lord Kalvan, is working hard at this and constantly frustrated by the limits of his own technological knowledge.
- Our Time Travel Is Different: The Ghaldron-Hesthor conveyor goes sideways in time rather than up or down. Paratimers believe past or future travel is impossible. Sitting inside one's Ghaldron-Hesthor field one can watch the rise and fall of civilizations through the dome as one travels. Occasionally the experience gets a little too up close and personal. Fatalities are not unknown.
- Past-Life Memories: Hadron Dalla works out a way to retrieve these with unforeseen consequences in Last Enemy
- Reincarnation: A proven scientific fact in this 'verse with interesting social consequences on at least one timeline.
- Retro Rocket: Paratimers use these to cover continental distances and get from conveyer head to conveyer head in their own Sectors.
- Scam Religion: Paratimers have absolutely no problem with subverting out-time religions as a cover for their activities. To be fair the one Scam Religion we see in detail, in Temple Trouble goes out of its way to be harmless and mildly positive in its effects.
- Sleep Learning: Via drugged hypnosis is how Paratime agents get the languages and customs they need for their field work.
- Technology Marches On: see Zeerust below.
- Temporary Divorce: Verkan Vall and Hadron Dalla were briefly married about twenty years before her appearance in 'Last Enemy'. The marriage fell apart due to her free wheeling ways and his dedication to his job. Recruiting Dalla into the Paratime Police probably saves their second marriage from going the way of the first.
- Tin-Can Robot: These are everywhere on Home timeline as concierges or house servants.
- Zeerust: In 'Time Crime' Verkan finds investigators scribbling on sheets of paper and pinning them to a chart. He also uses a fax machine to get data from a branch office.