Fanfiction authors often do several stories without any continuity connecting them. For instance, the hero may be in a different situation in story B than they were in story A, while story C will be an AU whereas the first two were following the canon straight.
But then there are some that decide that they want to create more than just a one-shot, or a multi-chapter tale. They instead decide to give their stories a canon of their own, and, as such, each of their stories can pick up where the last left off. They could make a sequel to their own story, or they could begin a series fic (can also be called a serial fic due to the fic acting like a serial series on television).
In a series fic, each story follows a certain continuity with the one that preceded it. In fandoms, these can be tricky to pull off well due to the reader having to sift through several stories to catch up if the series runs on for long enough. Furthermore, the author needs to convey to the reader that not all plot lines are designed to conclude at the end of the story (in the case where a series is planned before the first story is made). Authors also must make readers aware that a particular fic is part of that series continuity, especially if the canon characters have grown into different people than their original depictions by the time the story chronologically takes place to a point where the reader might be put off if they don't realize that it is deep into it's own alternate timeline.
However, if done well, they can be seen as epic pieces, and could be a crowning moment for the author. Keeping someone engaged for as long as a series might last (or, as long as the author is willing to continue it) can be a feat in of itself, but to keep a sense of who the canon characters are while putting new flair to them for as long as it holds out is even more daring. The rewards are great, but the risk is just as large.
Series fics can be rather fun to write, as well, because authors can choose to leave the last chapter in a particular story in the series with a cliffhanger that can resolve itself in the first chapter of the next story in the series. They can also have some interesting situations that the canon characters can get into as a direct result of the story lines arching over multiple stories, and a cast of original characters that the author can be as creative as they want with (within reason, of course). As said before, greater risk can lead to a greater reward.
Most authors will, in this sense, make summary chapters in fics that are included in these series so the reader can get caught up without having to reread dozens of chapters of the previous fics to have the same effect. They can also direct them to places where they can get caught up (such as a website devoted to their series fic) if they are more comfortable with that method.
Series fics can begin at mainly any point in the source canon. However, once it starts, the series can steer off in its own direction with the stories and with its characters. Because of the nature of series fics, more tolerance of original characters, and canon character going out of character after a certain amount of the series has been played out, are given if it's an ongoing series with no set end point.
Compare Alternate Universe Fic (which these sometimes are), Continuation (those can become series fics in their own right), and Original Flavour (which many series fics are known, to a lesser extent, to have as a rule).
- Dark Mark's The DCU Fan Verse started with an alternate universe single story. Then he started writing more and more sequels, creating the Kara of Rokyn series. Then he wrote the Hellsister Trilogy subseries -plus other fics set in that continuity-, A Force of Four, Here There Be Monsters, and other stories set in parallel universes created by the events of Kara of Rokyn.
- "A song of Sun and Shadow": Created by Finmonster, this shared universe has several stories now including Heaven's Light, Seven Days in Corona, The Dragon and the Bow, The Legend of Gobber the Belch, and When the Cold Wind is a Callin'.
- The Great Disney Adventure Saga: A trilogy of fics dealing with a family getting stuck in a Disney Mega Crossover trying to get home.
- The Little Pony Legend: A series of several fics set in a Fusion Fic universe of The Legend of Korra and My Little Pony: Friendship Is Magic.
- Transformers: Avatar Chronicles. Written by The Bane of Humanity, these 5 fics chronicle how the autobots and decepticons got their wars for power and freedom tangled in the world of the Avatar.
- Project Bluefield is one, featuring an Original Generation of Original Characters who travel between worlds.
- Child of the Storm is the first book of a multi-volume series. To date, it has one complete brief spinoff and one ongoing sequel.
- Memories of Heian is a series of Touken Ranbu/Onmyōji crossovers. To date, it has 3 stories: Tsuki ya aranu, Mononofu and The First Saniwa.
- A Song of Metal and Marvels is a series of A Song of Ice and Fire/Marvel Comics crossovers. As of now, the original story, A Man of Iron, and the second book A Crack of Thunder, are complete , and a third book, A Shield of Man, is ongoing.
- A Gem in the Rough is a One Piece and Steven Universe crossover series where a gem artifact sends Steven into the One Piece world where he meets Mr. 5 and Miss Valentines Day. It currently has two parts, the titular A Gem in the Rough and the sequel Gems Without Measure; A Pirate's Treasure.
- The Multiverser Saga is a series of collaborative fanfictions about multiversal gods travelling the Multiverse and getting involved with different works of fiction they enjoyed, often bringing aspects of different worlds into other worlds, while their enemies do the same in a much more destructive fashion.
- Tokimeki PokéLive! and TwinBee is a Pokémon, Love Live!, Tokimeki Memorial and Twinbee crossover fanfic series that is a crossover between the Main Series Pokémon games, Love Live! School Idol Festival and it's ALL STARS sequel, the Kirameki and Hibikino sagas of TokiMemo and the Twinbee games that star Pastel and her cousin Light. In addition, it is also a part of the IdolMon Multiverse, a series of crossovers between mons and Japanese Idol series.
- The Misfits Series by Red Witch is a crossover between X-Men: Evolution and G.I. Joe: A Real American Hero, where the Brotherhood of Mutants leave Magneto and get adopted by the Joes, becoming the titular Misfits.
- Marvel Cinematic Universe
- Alexander Pierce Should Have Died Slower
- Assembly Line
- Bringing the War Home
- Infinite Coffee and Protection Detail
- The Making of Monsters
- Second Chances Series is series of fics where Tony Stark's parents come back to life sometime after Captain America: Civil War and deals with the aftermath of their resurrection and the Civil War.
- Star Wars
- Avantasia Protag AU is a series based off the premise of the four protagonists, one from each Rock Opera story arc, living together as roommates in the present day. It consists of individual non-sequential chapters in "angst" and "fun" collections and several multi-chapter stories. There is an official timeline to assist readers with the order of events. Despite the main storyline set in the present day, occasional dimensional travel allows the characters to temporarily return to their original "worlds" of the albums for additional adventures.
- The Danganronpa series fic Danganronpa: The Immersive Learning Program focuses on mixing the cast from the three main series games and placing them into three distinct killing games. The current entires are Danganronpa: The Immersive Learning Program, Danganronpa: Academy of Discontent, and Danganronpa: Semester in Hell.
- New Island Life focuses on a retelling of Danganronpa with the inclusion of Original Character Sora Rikkido and Jiraiya Hojo, as well as few less prominent ships in the fandom. New island Life is the first to be published, followed by the prequel New school life and the sequels New Hope and Despair and New School semester.
- Time Fixers: Nicktoons of the Future is a Spin-Offspring of Nicktoons Unite! that spanned for four seasons.
- The Bolt Chronicles: While all these stories are one-shots, they interlock chronologically and maintain continuity.
- Danny Phantom
- Invader Zim: The New Adventures of Invader Zim is currently only composed of one complete "season", with another one currently underway, with Word of God that it's meant to have several more after that.
- Land Before Time Retold: While a Re Write of The Land Before Time, it adds its own twists into the story as well. Currently on movie 6.
- The Legend of Korra: The Saga of Avatar Korra is a series of fics that is an alternate universe rewrite of The Legend of Korra beginning with the Red Lotus's successful abduction of Korra as a child.
- Miraculous Ladybug
- Smart Adversaries AU is a series of fics that ask What If? an adversary makes a smarter decision. The series is ongoing, with 47 entries so far, each complete.
- The One to Make It Stay is a series of fics of what would took place after if the band, Kitty Section, found out about Lila's lies and become Marinette's support group.
- Burning Bridges, Building Confidence is a series of fics where Cole, Marinette's cousin, moves to France, goes to Marinette's school, and becomes her ally...in more ways than one.
- My Little Pony: Friendship Is Magic:
- The Elements of Friendship is an ongoing series of re-dramatizing episodes of My Little Pony: Friendship Is Magic as epic High Fantasy.
- The Flash Sentry Chronicles: is a My Little Pony: Friendship Is Magic fanfiction retelling in an Alternate Universe with Flash Sentry playing a main role. This story adapts all the seasons and movies and is currently on season 6.
- The Pony POV Series. Starting with season 2 of My Little Pony: Friendship Is Magic, and creating its own vast expanded universe.
- Puppy in My Pocket: Adventures in Pocketville
- Nihonverse Pocketville is an ongoing Dark Fic fanfic series that is loosely based on the show (some aspects have been changed to the author's liking), and is about Pocketers finding out the secrets of their kingdom and going on quests and adventures so they can receive an honor by Queen Ava. So far, the first fanfic from it is a Crossover, Pocketville Twilight.
- Monster Chronicles is an ongoing 'Total Drama'' Dark Fic fanfic series starting with Voodoo's Disciple and it on it second story Malevolence.
- The works of Angelus-v1 in creating his own Young Justice universe. He currently has 4 fics in his universe with several more planned. The ones created thus far: Young Justice: Darkness Falls, Young Justice Titans, Young Justice Thanksgiving, and Young Justice Vow.