History Literature / StarTrekDepartmentOfTemporalInvestigations

** The DTI and their 29th-century, 31st-century, etc. equivalents. The DTI dislike the 29th century for their incredibly reckless approach to time-travel (as seen in "Relativity"), arresting people for crimes they haven't committed ''yet'', and just being smug berks.

* FantasticNatureReserve: The Collectors desire to create one of these for themselves. The temporal devices they send back for this purpose are timed to grab a sample of a given species just prior to their extinction (to minimize any disruption to the timeline their absence may cause) and bring them forward in time. The misadventure caused by Starfleet's premature discovery of one such device prompts a re-evaluation of their plan.

* BullyingADragon: Apparently there are people who've tried antagonising the Vedala. Exactly what happened next isn't specified, only that the results are legendary.

Part of the Literature/StarTrekNovelverse. A DayInTheLimelight for the titular [[TimePolice Department of Temporal Investigations]], which monitors the integrity of the timeline and protects the history of the ''Franchise/StarTrek'' universe from attempted [[CosmicRetcon Cosmic Retcons]].

* LeaningOnTheForthWall: Seeing a Vedala at the end of the book, Kirk thinks to himself their bipedal stance looks a little cartoonish. Which they would, given they debuted in ''The Animated Series''.

* HoistByTheirOwnPetard: The Romulans of the alternate timeline made the Vulcans militaristic in preparation to invade them. ''Somehow'', this wound up with the Romulans getting conquered instead.

* MythologyGag: When seeing the ''Enterprise'' being refit, Scotty mentions a fellow called Probert who's got some good ideas about ship-design. Probert was the name of one of the conceptual artists involved with ''TNG''.

* TimeCrash: A time travel experiment [[GoneHorriblyWrong Goes Horribly Wrong]] creating a "confluence" where the past and present of two separate timelines overlap, with the potential that people could stumble between universes and / or times and accidentally rewrite each others' histories.

* BigDamnHeroes: At the conclusion, the ''Enterprise'' is saved from a Compact ship by... [[spoiler:Command T'Pring, from the alternate timeline's 24th century.]]

** In the {{Flashback}} sequence, Spock is surprised that his human collegue thinks of [[Recap/StarTrekS1E8Miri the Onlies planet]] (a parallel Earth where most of humanity died) as "home". He then reflects that he doesn't know how he'd react if he encountered [[Film/StarTrek2009 a timeline where Vulcan was destroyed]].

* ExactWords: Simok tells that Spock and alternate!T'Pring are working on a way to solve the problem and increase their efficiency. Fortunately, no-one asks why this requires them to be alone and out of communication for two days...

** The mission that ends ''Enterprise'''s five year journey is filled with them. Chapel, having given up on her crush on Spock, is thinking of becoming an M.D.. Kirk's getting bored with the heartbreak of captaining and is looking to pack it all in. Spock reflects on the many times he's lost emotional control over the original and animated series, thinking maybe it's time he got around to taking the kohlinahr.

* ChekhovsGun: It's made clear early on that the star slingshot method of time travel only works with the Enterprise's unique chroniton-emitting engines, due to an unreplicatable accident in [[Recap/StarTrekS1E4TheNakedTime The Naked Time]]. However, Kirk was later able to do it with a run-of-the-mill Klingon ship in [[Film/StarTrekIVTheVoyageHome The Voyage Home]]. DTI agents have long been frustrated trying to figure out ''how'' Kirk pulled that off, and it's one of the main reasons why they dislike him. In the climax, [[spoiler:Lucsly and Kirk are trying to solve a TimeCrash, but while the former's Technobabble is insufficient to directly solve the crisis, Kirk relays enough of it to Spock and Scotty that they are able to figure out how make their current engines emit chronitons, which helps fix both the current problem and the whale probe crisis much later.]] Lucsly, for his part, is unhappy when he figures this out, but begrudgingly goes along with it.

* TheRedBaron: DTI agents of the 24th century refer to Kirk as "the Time Pirate".

* YearOutsideHourInside: This is how the eponymous time lock protocol works, causing time to slow within the Eridian Vault at an exponentially increasing rate. Thus the dilation is small at first, but within hours will reach the point where minutes inside are months, years, or even decades outside.

* WidowWoman: Alternate T'Pring lost her version of Stonn to war. On the plus side, her grief from losing him means she's a hell of a lot more empathetic than her counterpart.

* BreakTheBeliever: Lucsly has an almost religious conviction that there is one, and only one, "true" timeline in the universe. This is how he keeps himself grounded when faced with the oftentimes overwhelming scope of temporal multidimensionality, which is why it is such a blow when he learns that this may not be the case. When their [[TeethClenchedTeamwork (sometimes)]] friends from the future intervene in the prosecution of Janeway for her myriad temporal violations in the Delta Quadrant, and it's revealed that DTI's version of history is "wrong" compared to theirs, Lucsly endures a crisis of faith which, like so many others from the department, [[FriendshipMoment he needs his partner to shake him out of]].

* ''Literature/StarTrekCoda'': A Crisis Crossover and Grand Finale for the Novel Verse. Given the nature of the Trilogy's crisis (i.e. the ''Temporal'' Apocalypse), the DTI plays a signigicant role.

* ''Literature/StarTrekCoda'': The Grand Finale of the Novel Verse. Given the nature of the Trilogy's plot (i.e. the ''Temporal'' Apocalypse), the DTI's is part of the Crisis Crossover.