History Main / TheConstant

** The area that the main cast is exploring used to be mainland Denmark, but the nation itself survived as a tiny island. The Denmark segement of the prologue focuses on someone from the mainland getting stuck on the small island in question because of sudden travel restrictions. The newscast announcing the travel restrictions mentions a couple of locations that become relevant in the early leg of the main cast's journey ninety years later.

* In ''FineStructure'', Anne Poole is the Constant for over 20,000 years.

* In ''Series/TheFlash2014'', according to Earth-2's Harrison Wells, "Every earth has ''Film/TheGodfather''".

* ''VideoGame/TheLegendOfZeldaOcarinaOfTime'' and ''VideoGame/{{The Legend Of Zelda Oracle|Games}} of Ages'' play with this trope a lot. It's possible the Deku tree is an example across the games, if the one in ''VideoGame/TheLegendOfZeldaTheWindWaker'' is the same one in ''Ocarina''. (More likely, it's the tree that grew out of the Deku Sprout, since the old one died.)
** In ''VideoGame/TheLegendOfZeldaBreathOfTheWild'', while the towns that weren't destroyed in the Great Calamity have been remarkably well-preserved in the century since, Revali's Landing and the Thunder Helm are two things from back then that are specifically pointed out to Link due to them being associated with the old Champions Revali and Urbosa respectively. Indeed, having those pointed out is enough for him to recover his memories of his old friends.

** White London is slowly being drained of its magic and its life energy. The White dimension is currently undergoing a bloody, neverending civil war, with the leader (or leaders) of White London changing every few years. People there are willing to do ''anything'' to get a bit of magic power.

** Círdan the Shipwright is one in-universe. He has been around in so long (tens of thousands of years, making him the oldest known elf still there at the time of LOTR) that he is the only elf ever mentioned that has managed to ''grow an actual long grey beard.'' And he (or one of his two ports) is at the very least mentioned in almost every major work to do with Middle-earth.

** Our own dimension is the Grey London, the one without magic, and is usually seen as unchanging but sturdy and long-lasting. Things in Grey London can weather almost anything.

** In the old series, there was only one actor who crossed the tenures of more than two Doctors: TheBrigadier. Even TheMaster and Davros changed actors. But Nicholas Courtney was there as Brigadier Alistair Gordon Lethbridge-Stewart from the second doctor, to the seventh, making his final appearance in the Sarah Jane Adventures. Companions changed, and the Doctor regenerated, but the Brigadier stood there throughout it all, always taking TheSlowPath, and always ready to [[CrowningMomentOfAwesome do the best he can.]]

* In ''WesternAnimation/TheFairlyOddParents'', when Timmy changed the past and ended up living in a terrible foreign country called Ustinkistan (inside hasn't been invented, the nights last 11 months, during which werewolves are on the prowl, and the last boat to every leave the country sailed fifty years ago), Timmy was forced to use a turnip time machine to go back in time and change the past back. After using the machine, Timmy noticed that everything was still the same, leading him to believe that the time machine didn't work. Wanda then tells him it did and he was now fifty years in the past. As she noted "Not much changes here in Ustinkistan".

* Happens several times to the immortal Kaim, in ''LostOdyssey''. A couple of incidents in the 'Dreams of a Thousand Years' section involve him meeting someone as a child, then crossing their paths again, 60, 70 or 80 years later, where they're old and dying, and he's still as young as ever. In the main game story, he also meets a wise old king - whom, as it turns out, he first met when he was a brash young prince, and taught a few things about combat, survival, and life in general.

** In ''Literature/ManifoldSpace', Reid Malenfant and Madeleine Meacher becomes increasingly isolated from mankind as they are thrown system to system at the speed of light. Every time they return to Sol, [[FishOutOfTemporalWater mankind has changed]] and not necessarily for the better. However, every time they return they cross paths with Nemoto, a manipulative, paranoid, and [[TheAgeless seemingly ageless]] Japanese astronomer who works behind the scenes to protect mankind from her 'alien threat'

* Happens from time to time in ''Series/DoctorWho'' due to its time-travel nature. A significant example comes during the last episode of the new Series 5, [[spoiler: where events are put into place that makes Amy Pond the constant for the entire universe.]]

** In the old series, there was only one actor who crossed the tenures of more than two doctors. TheBrigadier. Even TheMaster and Davros changed actors. But Nicholas Courtney was there as Brigadier Alistair Gordon Lethbridge-Stewart from the second doctor, to the seventh, making his final appearance in the Sarah Jane Adventures. Companions changed, and the Doctor regenerated, but the Brigadier stood there throughout it all, always taking TheSlowPath, and always ready to [[CrowningMomentOfAwesome do the best he can.]]
*** And that's what makes it so [[TearJerker heartbreaking]] when you find out he has died by the time of the Eleventh Doctor.

** The Second Doctor story "The Ice Warriors" is set in a future Ice Age, full of snow and glaciers. But the human scientists' base is an old Queen Anne mansion (including the furniture), making it recognizably our future (probably England). There's also a present- or past-style nursery shed.
** The Doctor himself becomes this for [[spoiler:Clara Oswald]], as revealed in [[Recap/DoctorWhoS33E13TheNameOfTheDoctor the series 7 finale]].
--->Sometimes it's like I've lived a thousand lives in a thousand places. I'm born. I live. I die. And always there's the Doctor.

* In ''Series/TheFlash'', according to Earth-2's Harrison Wells, "Every earth has ''Film/TheGodfather''".

** The area that the main cast is exploring used to be mainland Denmark, but the nation itself survived as a tiny island. The Denmark segement of the prologue focuses on someone from the mainland getting stuck on the small island in question because of sudden travel restrictions. The newscast announcing the travel restrictions mentions of a couple of locations that become relevant in the early leg of the main cast's journey ninety years later.

** In the JustBeforeTheEnd prologue, the Finland segment focuses on an extended family that includes a couple by the name of Hotakainen that are expecting their baby to be born in the next few weeks. In the main story set ninety years later, the cast includes three Finnish young adults with the Hotakainen surname, who occasionally mention their grandmother. The family tree published at the end of Chapter 12 eventually confirmed that the unborn baby from the prologue and "grandma" were indeed the same person.
** The area that the main cast is exploring used to be mainland Denmark, but the nation itself survived as a tiny island. The Denmark semgement prologue focuses on someone from the mainland getting stuck on the small island in question because of sudden travel restrictions. The newscast announcing the travel restrictions mentions of a couple of locations that become relevant in the early leg of the main cast's journey ninety years later.

* VandalSavage acts as this sometimes for the DCU, since his complete unkillability allows him to survive pretty much any changes that would kill off everyone else.

* Lampshaded in the Literature/{{Discworld}} novel ''Discworld/WyrdSisters''. The biggest expense of TimeTravel is finding a fashion store that will remain open for 50 years in the exact same place.

* [[InvertedTrope Inverted]] in the Literature/{{Discworld}} book ''Discworld/NightWatch''. Sam Vimes ends up in the past after a magical accident, and has to keep things on-track while a criminal who went with him is messing everything up. Right when he's most despairing of ever getting back to where he belongs, [[spoiler: a History Monk brings him his silver cigar case, a gift from the wife he doesn't have yet and a reminder that his 'future' is real and has already happened.]]
** On the other hand, many of the important cast members' past selves feature in the story: Fred Colon, M(r)s. Palm, Young Vimes, [[spoiler: Vetinari]]...

* Demona in ''WesternAnimation/{{Gargoyles}}''.

* In ''VideoGame/{{Fallout 4}}'' the Protagonist is Cryogenically frozen, their spouse killed, and his son kidnapped. Their robotic butler, Codsworth, exists as a constant between the pre-war and post-war times. The Vault-Tec Salesman who sold you your place in the Vault can also be found and recruited, however he has undergone 'Ghoulification' due to the radiation damage.

** [[spoiler:Although WordOfGod states that it does in fact topple.]]

* In ''Series/TheFlash'', according to Earth-2's Harrison Wells, "Every earth has ''Film/TheGodfather''.

* In ''TheChroniclesOfNarnia: The Silver Chair'' the heroes are directed by Aslan to go to the Ruined City of the Giants and look for [[PlotCoupon a sign]] that would tell them where to go. Not seeing anything, they are trapped in a snowstorm and forced to hide in a series of trenches. They [[ThatsNoMoon realize their mistake later]] when [[TheRuinsICaused returning to the site]], they see the trenches were actually letters on a giant inscription:

** And in ''Prince Caspian'', the Pevensies return to Narnia and Susan finds one of their old chess pieces, and they realize that they're in the ruins of Caer Paravel.
* In UrsulaKLeGuin's short story "April in Paris", the protagonists occupy the same apartment in different centuries. Notre Dame is another Constant.
* In ''TheTimeTravelersWife'', Claire generally serves as Henry's Constant as he jumps around in time.

* A ''StarWars'' novel has someone who was nearly killed at the end of the Clone Wars and put into stasis for at least half a century, awaking long after the ''original'' movies. With almost everyone he knew long dead and the galaxy having gone through several wars and governments, he decides to search for a specific Constant, the YT-1300 freighter he was flying on the mission where he nearly died - the ship that has since come to be known as the ''Millennium Falcon''.

If the time traveled was too short, there may be so many Constants that it's unremarkable. For example, it's not uncommon for the entire cast from the past to switch to FutureBadass versions of themselves in the future. On the other hand, there is no minimum time difference - a city may be reduced to an unrecognizable place overnight by a terrible weapon, except for The Constant proving it was there. Or as Nena would say, "If I could find a souvenir / Just to prove the world was here."

* In Literature/TimeSpiral, the type of time travel that Karn uses to go back in time to when he can seal the rift in Tolaria requires a solid link of related memories going back to when he needs to travel to. He uses his memories of his friendship with Jhoira.

* In Creator/DianaWynneJones's ''Literature/TheHomewardBounders'', the Old Fort - in particular, the statue on the grounds - are the Constant. [[spoiler:So are the canal arches, and the sign identifying the former Churt House.]]

** Averted when Nevyn, now a royal adviser, tries to find his old quarters in the royal broch in Dun Deverry - and cannot, because the complex has been repaired and expanded so many times over the centuries since he was condemned to WalkTheEarth.

* In Creator/HBeamPiper's ''Lord Kalvan of Otherwhen'', the absence of an expected constant - the stone quarries of an area of Pennsylvania that the protagonist knows quite well, and which could not have eroded while leaving the local geography intact - tips him off to the fact that he has ''not'' [[TimeTravel travelled into the far future]] as he previously thought, but is in an AlternateUniverse.

* A ''StarWars'' novel has someone who was nearly killed at the end of the Clone Wars and put into stasis for at least half a century, awaking long after the ''original'' movies. With almost everyone he knew long dead and the galaxy having gone through several wars and governments, he decides to search for a specific Constant, the YT-1300 freighter he was flying on the mission where he nearly died - the ship that has since come to be known as the ''Millenium Falcon''.