Story's over. The Hero and the Love Interest have married, settled down, have no further interest in adventures - and, besides, who would look after the kids while they saved the world? Or perhaps - gasp - he died and stayed dead.
And they want a sequel.
What's a writer to do?
Why, promote the Sidekick of course. Or an ally. Or a brother or child. They haven't married and settled down yet. The Hero and his Love Interest can serve as supporting characters (and prove that they are Happily Married as a sidenote). Or the Heroic Bystander, or the Heroic Wannabe - any character that wasn't the lead can fit, if only they are promoted to lead. A Sequel Hook about their story helps, but is not required. Even new characters who have plausible relationships to the old story, such as the childrenThe Hero and Love Interest could have - or the child the Love Interest is about to have, even if she wants to make sure he doesn't Turn Out Like His Father.
Any story is possible; the Changing of the Guard may be invisible to the characters, behind the fourth wall. However, Changing of the Guard often has the new main character move in the old character's role, and this can be noticed - from as subtle as a character twitting someone in love, because earlier in the series, when heart-whole and fancy-free, he had mocked lovers, to as formal and overt as a character handing on the responsibility - which may be a Happy Ending if he is glad to leave, a Bitter Sweet Ending if the character has at least some longing to go on, or a Downer Ending if The Hero died, and another character must Take Up My Sword.
Compare with Legacy Characters. When done for the right reasons, an excellent way to avoid Plot Leveling. Then, it may be dictated by real life, if an actor refuses to return, or even to increase merchandizing opportunities. These are generally less fortunate. Can lead to Generation Xerox, which is usually not done for the right reasons. Contrast Old Hero, New Pals. If done repeatedly within one storyline, it's The Rashomon.
Digimon Adventure 02 picked up where the first left off by having the two youngest kids team up with a whole new group, while the older heroes served as mentors.
Mobile Suit Gundam Seed primarily focuses on Kira. In the sequel, Gundam Seed Destiny, Kira and his love Lacus are happily living together with a score of orphans, and the focus shifts instead to Kira's friend Athrun and a younger Gundam pilot, Shinn. About halfway through the series, Kira and Lacus came back as the primary protagonists alongside Athrun.
JoJo's Bizarre Adventure passes the torch to a different Joestar every new series, although they usually wind up in conflict with Dio (even indirectly) at some point. It's also common for supporting characters in one series to show up in another, like Polnareff's involvement in Part 5.
Mai-Otome changes the main character from Mai to Arika in both versions, but the nature of Mai's eventual reappearance is very different between the two adaptations.
Tishe Record of Lodoss War OVA switches halfway through from Parn to Spark as the main character. Of course, he's actually just being Bad Ass offscreen, and returns just in time for the Final Battle.
Similarly, the second season of Superbook had Gizmo team up with a young friend of the main characters of the first season, Joy and Chris. They kept in contact with them through a communication screen in Gizmo's stomach (he's a robot).
Akira Toriyama wanted to do this in Dragon Ball Z, switching the focus from Goku to his son Gohan, but the audience and the publisher kept demanding more Goku.
It has been said that he originally did want to change from Goku to Gohan, but switched the main focus back to Goku because he decided that Gohan wasn't fit for the role.
His notes for the end of the Cell Saga have confirmed he intended for Gohan to fit the role. Likely Executive Meddling and a combination of fan love for Goku as well as the reason listed above probably resulted in Goku becoming the main hero again.
With every new arc and region of Pokémon Special comes new protagonists, with the old ones occasionally providing backup. The best thing about this is that since the focus isn't on one character all the time, nobody suffers from Badass Decay.
In a controversial decision, the folds in charge Ultimate Spider-Man allowed Peter to be killed off. A successor named Miles Morales took upthe mantle, despite being younger, smaller, and afraid of his powers.
Indiana Jones and the Kingdom of the Crystal Skull introduces Indy's son Mutt, who may get a film of his own if Spielberg wants to make another film. Even so, the film ends with a pointed subversion of passing the torch as Indy's trademark hat is blown off its rack and Mutt picks it up. He's about to try it on when Indy snatches it back.
Like the Indiana Jones above, Rocky Balboa had a perfectly good opportunity to pass off his Best Boxer EVAR mantle to a young man named Steps (who did not have any other purpose to the story). He doesn't, though.
A meta-version of this occurs in the beginning of The Rundown when The Rock enters a club and passes Arnold Schwarzenegger, who wishes him a good time as he's leaving the club.
An odd example occurs with the Van Wilder series. The first movie focuses around its titular character. The second movie then shifts focus to the sidekick, Taj. The third movie then returns to Van, the main character from the first movie.
Bruce Almighty starred Jim Carrey as Bruce... and as a supporting character, Steve Carell as newscaster Evan. Steve's character would then get promoted to the lead role in the sequel, Evan Almighty.
Skyfall does this for James Bond's supporting cast. By the end of the film Judi Dench's M has died, been replaced by Ralph Fiennes' male M and we are introduced to a new Moneypenny and Q. The more things change, the more they stay the same.
Raymond E. Feist's Riftwar Series. While most of the powerful magicians are long-lived, supporting characters in the later books are typically descendants of the original protagonists. Famous examples are the descendants of Duke Borric and Jimmy the Hand.
J. R. R. Tolkien wrestled with the idea of having Bilbo have more adventures after The Hobbit, but quickly decided on having a son or other relative have them instead, although it took him a while to decide on Frodo.
Edgar Rice Burroughs played with this in his Mars books. After the third book, he began writing about a larger stable of viewpoint characters, as John Carter's own romance arc had been completed and he needed new princesses to rescue and heroes to rescue them. John Carter remained a central figure and The Hero throughout the series, however
Andre Norton's Witch World started with two books about Simon Tregarth. Then she wrote them about his children, or about other characters in the same world.
Half of the "Mirror Dance" has Mark as the main character and the audience point of view. So, McMaster actually changed of the guard twice during the book.
Ethan of Athos qualify also for this trope, as the book is focus on Elli Quinn and Ethan.
Lois McMaster Bujold has done this again with the first two Chalion books. Amusingly, the heroine of the second one is the mother of a supporting character in the first.
Done constantly in Xanth. What generation of Bink's family are we on now?
Averted in the same author'sIncarnations of Immortality, because most of the important protagonists are immortal, so characters from the 1200s mingle with space-age teenagers without missing a beat.
In the Apprentice Adept series, this is played with. The main characters in Book 4 and 5 are from the second generation, but in Book 6, the first-, second- and third-generation heroes all get equal screen time and are equally relevant to the plot.
Heralds of Valdemar does this, but just as often in reverse, recounting the experience of past generations rather than future ones. And then the children of past generations take the torch, but still in the past. And then their great-great-great-grandchildren show up in the present novels.
Terry Brooks' Shannara series does it regularly. The grandchildren of the characters of previous book typically become the protagonists of the next. Suffers from Generation Xerox somewhat.
Redwall: There's a new set of characters is almost every book. The only constant is the the abbey itself.
And there are a few novels that predate the construction of the Abbey, so not even that is entirely constant.
Dragonlance Chronicles has Tanis as its lead character but its sequel Legends set shortly after has the twins Caramon and Raistlin take the spotlight. The next book set years later has the children of the heroes from Chronicles as the main cast.
The Sacketts series by Louis L'Amour has this built-in and happening over and over. As the title suggest, the series is meant to be about the Sackett family, not one particular hero.
Every new one of The Chronicles of Narnia has a new changing of the guard: First, there were the 4 Pevensie siblings. Then there were two and a cousin. Then the cousin and a friend... The prequel even established a minor character from the first published book as the major character in a previous adventure.
In Jacqueline Carey's Kushiel's Legacy books, the first trilogy is narrated by Phedre. The second is by her adopted son, as Phedre is semi-retired from adventuring by the time he's an adult.
The Edge Chronicles features a new set of characters across almost every book. The whole series has three trilogies, each with a different central protagonist.
Rick Riordan's The Lost Hero centers about three entirely new demi-gods, not Percy Jackson and his friends.
The first four books of the X-Wing Series had Wedge Antilles and Rogue Squadron, but the primary focus was unmistakeably Corran Horn. Those four books ended with the Rogues, including Wedge and Corran, deciding to help a planet's defenses build up after "killing" the Big Bad. The next three books were to be written by another author, who wanted to write from the POV of some of Wedge's friends creating a new squadron. Executive Meddling nixed this, so Aaron Allston had Wedge leave the Rogues for a while and create a new squadron himself. Some other characters are in common, but in different or reduced roles.
Mercy Kill, the 10th X-Wing novel, happens after a 20 year Time Skip, and a new generation of Wraiths are introduced
The first series of the Warrior Cats books started off with Firestar as the main character. He was then replaced by Brambleclaw, his former apprentice, in Warrior Cats: The New Prophecy. In Power of Three, Brambleclaw turns into a background character like Firestar, and is replaced by his adopted children Jayfeather, Lionblaze, and Hollyleaf. Omen of the Stars has Ivypool and Dovewing, two younger cats, as its main focus, with the Power of Three characters still in tow.
Most of the main good guys from the first three Emberverse books have a lot of authority in the new nation-states by the time the second series rolls around. This would put a crimp in their ability to go haring off to find the Sword of Plot Advancement when such a trip would take several years - a fact the resident Tolkien geek deeply laments - and so the task falls to the previously established Chosen One, his childhood friend, and seven more characters who either could be missed by blinking in the first three books or are completely new. While they're away, we do get the occasional glimpse of the old guard struggling to stave off the new Big Bad.
Mort and Ysabell's story ended with them Happily Married. So for the next novel that needed a young clueless human to take on Death's role and mess things up, their daughter Susan was introduced.
Lords and Ladies also ends with Magrat, the Maiden of the Lancre coven, getting married. Luckily, the same novel introduces a coven of young girls messing about, one of whom — Agnes Nitt — actually has some talent and becomes Third Witch (eventually) in the next coven novel. Arguably, the Tiffany Aching novels mark a Changing of the Guard for the entire witches series, with Tiff becoming the main character while Nanny and Granny fade into support roles.
After a while, the Thoroughbred series stopped focussing on Ashley and her friends and timeskipped a few years to focus on their kids instead.
Power Rangers did a lot of this in its early seasons: when old actors left or started getting too old for their roles, they transferred their powers to new ones and went off to do stuff.
The War of the Worlds series did this when it switched into a Darker and Edgier season, throwing out decayed villains and immediately establishing the threat of the new ones with the death of two of the ensemble. Their mourning was short-lifed due to the addition of Adrian Paul as an Anti-Hero.
In M*A*S*H this happens to several major cast members: Henry's tour of duty ends, he gets killed on his way home, and is replaced by Sherman Potter. Trapper goes home as well, in comes BJ. Frank breaks down, and is replaced by Charles. When Radar leaves, Klinger takes over his role as the company clerk.
Agent John Doggett replaced Fox Mulder as the male lead after the latter was abducted by the aliens in the eighth season of The X-Files. In the ninth season, Monica Reyes replaced Dana Scully as the female lead, completing the guard change.
Happened frequently in Law & Order; probably could have gone on forever if the network hadn't pulled the plug.
In the last season of JAG it looked like they were preparing for this—-the General replacing the Admiral, and the two younger lawyers being introduced.
The ending of Neverwinter Nights was set up for another adventure, but they move on to entirely new groups of heroes in the expansions and the sequel.
Most games in the Castlevania series focus on a different Belmont, although sometimes they're not available due to plot purposes, like in Bloodlines, Symphony Of The Night, and Portrait Of Ruin.
Later installments of the Kings Quest series focus on the adventures of Graham's (the original protagonist) descendants.
Eternal Darkness levels end (which often involves the death, or worse of said character) although it still has a protagonist who's played in the intervals between chapters.
Fire Emblem: Genealogy of the Holy War skips 17 years after its halfway point, so pretty much your entire army will be replaced by the children of your units.
This trope works backwards in the Elibe games. Blazing Sword (or just Fire Emblem outside Japan) was a prequel to Sword of Seals, so it naturally starred the parents of several of that game's characters.
Chrono Trigger and Chrono Cross. The main characters from the former are all out of the picture somehow (dead, in another time, or busy elsewhere), but before they left they set up an unimaginably complex Gambit Roulette to produce the main characters of the latter and get them to be in the right places at the right times.
Apollo Justice takes over from Phoenix Wright in the Ace Attorney games. Well, he technically does - the fact that the entire Apollo Justice game centres on what happened to Phoenix left some fans unconvinced. Still, Phoenix's pals were absent, to allow for a new cast.
It actually was suppose to be a whole new set of characters but Executive Meddling caused it to include Phoenix and the writers had to make it so that Phoenix couldn't just swoop in and save the day.
The son of the main characters from the previous game is implied to the new hero in Final Fantasy IV: The After Years and the game also focuses a good deal on the other children of the previous heroes as well, but the old heroes are quite active in the story themselves as well.
Dragon Age II continues the history of Thedas post-Fifth Blight (which was depicted in Origins) but with a new lead character and a mostly brand-new supporting cast.
In Valis IV, Yuko Ahso, who Ascended to a Higher Plane of Existence at the end of Valis III, passes the Valis Sword to new heroine Lena Brande. Cham and Valna return as supporting characters.
At the end of Final Fantasy X, Tidus ceases to exist due to the fact that Jecht's existance as Sin was the only thing keeping him alive. Obviously, Square Enix couldn't make him the protagonist of the sequel, so the story centers around Yuna instead and her quest to bring him back.
At the end of Final Fantasy XIII, Lightning, Vanille, and Fang all die as a result of the plot, so they're out. Bring in Lightning's sister, Serah. Conveniently, Lightning, while in Valhalla (Heaven if you will), is able to summon Noel to give her some help. Vanille, Fang, Snow, and Sahz also make appearances, not counting DLC.
Puyo Puyo Fever was supposedly going to take place in a different universe from the previous games...but lo and behold, former protagonist Arle somehow found her way in, along with Carbuncle. Other classic Puyo characters returned in the sequel, putting them in the same continuity.
Scary Go Round started with the characters Tessa and Rachel (let's call them the "New Guard") as protagonists, but they were soon complemented with and eventually usurped by characters from John Allison's previous webcomic Bobbins. For a while Shelley, Amy, Tim, and Ryan (the "Old Guard") reigned supreme, but then a batch of younger characters, in particular The Boy and Strange Girl / Perky Goth Esther (the "Young Guard" along with their friends) gradually took over. In the final chapters of SGR, the younger siblings of the "Young Guard", mainly Lottie and Shauna (the "Kid's Guard") starred (and transitioned into the successor webcomic Bad Machinery).
The "Old Guard" remained until the end too: the very last couple of comics show Shelley saying goodbye to Amy and Ryan and leaving town. As Lottie is the sister of Esther's best friend and both of them have met Shelley, it's almost my case of Take Up My Sword in the investigating-local-weirdness game. Ryan and Amy still appear in Bad Machinery as supporting characters - Ryan is now Shauna and Lottie's teacher.
Red vs. Blue: After the end of the fifth season, the show was brought back with the miniseries Recovery One, which featured a new protagonist named Agent Washington in the starring role. None of the original main characters reappeared, and the only returning characters were Delta, featured in the first miniseries Out of Mind, and Wyoming, who appears briefly and without any lines. Washington continued as the protagonist into the next season, Reconstruction, where the original cast gradually joined him.
Almost happened with the G.I. Joe Movie as well, which was in production around the same time. The negative reactions from the audiences prompted the executives to rework the plot, allowing Duke to live. Still happened to an extent with Cobra Commander however.
Extreme Ghostbusters does what the above-mentioned Ghostbusters 3 planned to do: focus on Egon training a new group. The Real Ghostbusters haven't quite quit, though, and return for one two-parter.
Katara: "Aang's time has passed. My brother and many of my friends are gone. It's time for you and your generation to take on the responsibility of keeping peace and balance in the world. But I think you're going to be a great Avatar."
It was played with a little bit previously, as the Avatar is a constantly reincarnated series of heroes, and Aang was frequently compared with his previous incarnations Roku and Kyoshi. Korra gets it a little worse though as there are plenty of people living who still remember Aang.
