Original Flavour

Said of a Fanfic that attempts to emulate the tone, atmosphere and style of its inspiration as closely as possible. The goal of the Original Flavour fic is to seem as though the original author or production team could have thought it up. Even if it heads off into previously unknown and unexplored territory for that property, the story will emphasize the use of existing characterization, gimmicks and devices rather that introducing totally foreign ones.

If you are writing an original flavour fic, you don't introduce new characters or kill core characters, revise continuity, or do anything that is non-canon beyond the events of your story. Original Flavor is exactly like writing a spec script you could submit to the showrunner, but not necessarily in script form.

Note that some fandoms, especially those with looser story arcs, are easier to write in Original Flavour than others. It's also more popular for works with a distinctive style of writing and/or dialogue, as this is a particularly easy element to imitate.

Original Flavour has been the direct polar opposite of most other Fanfic types at one time or another. Because of the widespread prevalence of labyrinthine Fix Fic, our old friend Mary Sue, and florid Shipping, Original Flavor can be incredibly rare. Fun is also found in a self-imposed challenge to see how far a writer can go out of the lines without technically deviating from "canon", without becoming an overt Elseworld.

For when this treatment is done for individual characters rather than entire stories, see Sailor Earth. For fanfics that take this up a notch, see Script Fic.

Examples of Original Flavour include:

Examples are sorted by the medium of the work for which the fan work is written.

Anime and Manga

Rob "Kenko" Haynie's Girl Days is one of the best Original Flavour Ranma ½ fics currently in existence, in some people's opinions.
Edan R. is currently^[when?] writing a series known as Pokémon Mystery Dungeon: Legendary & Ancient Discoveries. So far, only one book in the series has been made, and it seems like it's still in the beginning of the plot.
- Book I
Read The White Dog for an Inuyasha Original Flavour fic.
Talya Firedancer's Gravitation fanfics were explicitly written to read like a typical script taken from the anime.
Neon Genesis Evangelion's RE-TAKE is has the same sort of occasionally Mind Screw-ey plot as the original Evangelion, the art is as good or better than the canon source, the characters are all perfect, and the eventually happy ending is completely believable, taking into account the characters and the situation. There's a reason RE-TAKE is considered by Asuka fans to be the true continuation and ending of the End of Evangelion.
- Except that for every fan who considers RE-TAKE a masterpiece, there's another person feeling conflicted about the plot direction it takes, particularly during the later stages of the story. Original Flavour may not always be a good thing.
Online Fanfic pioneer Ryan Mathews once participated in a hoax wherein an unfinished Dirty Pair fanfiction was released on UseNet as the purported "transcript" of a lost OVA. Apparently, it was Original Flavour enough for those who read it—the record shows some of the readers engaged in several weeks of frantic research.
The Suzumiya Haruhi fanfic entitled The Love Affair of Nagato Yuki (whose title doesn't prepare you for the various surprises inside—well, except one), received various praises comparing it with both the series and the novels.
Team 8, a fanfic for Naruto, really catches the flavor and feel of the show while not sacrificing originality or quality.
Neko Love Hina is a take on the Love Hina franchise by Kytranis that improves as you read it and is aiming for humor with every chapter. Still incomplete and updates sporadically.
Dragon Ball Multiverse is a webcomic that could easily be mistaken for official art by Akira Toriyama.
- So long as you ignore most of the "special chapters" (about the backstories of the various Alternate Universe characters), which are drawn by different artists and tend to look a little... off. For a good example, look at the disturbing facial expressions in the Bojack special, or the general awfulness (and somewhat excessive gore, compared to canon Dragon Ball or the main comic) of the Cell special.
The Axis Powers Hetalia fic An Incident and Jerusalem/Increments of Jerusalem play out (for the most part) like a classic Sherlock Holmes story, going so far as to capture Sir Arthur C. Doyle's narrative style. This stays consistent all throughout, even as Arthur casually outwits Holmes.
This Pendent Heart is a Princess Tutu fanfic stunningly similar to the tone of the original show, even despite being overtly shippy at times (it helps that the anime was, after all, a Shojo work). It also ties together and expands on a few plot threads, while continuing to develop the characters.
The Elemental Chess Trilogy, a series of Fullmetal Alchemist fanfics, was intended to be this. It apparently succeeded, since a few reviewers questioned whether the author was really Hiromu Arakawa writing under a fake name.
Spreading Their Wings and Another New World are two Robotech fanfics that follow the style and canon of the series.
Mado Of Stone Mill is a great Haibane Renmei original flavour that takes place a little after the events of the anime.
Of Science and Magics is one for the A Certain Magical Index franchise, with Touma becoming childhood friends with Mikoto.
Meet Nadeshiko, a Shugo Chara fanfic. It starts out as a generic rimahiko fanfic, but as the story progresses, it becomes a great sequel to the series.

Film

Until further notice, The Revenge of the Old Queen is a cleverly written fanfic for The Rocky Horror Picture Show.
The Joker Blogs. Barring the Fan Service Mythology Gags, everything is as Original Flavor as can be. This is multiplied to the nth degree considering the Joker's characterization in the series.

Literature

Not He Who Tells, an original short story written in the style of Stephen King. (Anyone who has actually read Stephen King's work will be floored by this guy's achievement.) The author is G. Norman Lippert, who has also written a Harry Potter continuation series.
Rich Drushel added to Bored of the Rings parodies of LOTR's Appendix A and Scouring of the Shire. The latter is intended to be fitted into the text between the final two chapters.
Emperor's Ward: A Ciaphas Cain Story captures the style of Ciaphas Cain yarns nigh-perfectly.
Quite a few fics for A Series of Unfortunate Events.
Astrokath has a particularly good take on the events shortly after Dragonsdawn in Dragon Days.
In which Frank Herbert's ellipses are severely abused: Good Surprises.
The Ollivander Children attempts to write in the style of the later Harry Potter books, or that failing, some of the best fanfiction - such as seen in Harry Potter and the Society of Orpheus and Bacchus and Interwoven.

Live-Action TV

Firefly fanfic writers seem to be obsessed with fulfilling this trope, a possible side effect of Firefly never getting enough of its own "Original Flavor" in the first place.
Todd Smitts' Cold Case fanfics, written as conventional episodes of the series down to the use of music of the period in the flashbacks.
- Smitts and others also began to write a fictional 8th season after the series was cancelled, picking some of the lines left loose at the end and even proposing actors for the new roles. You can read it here.
The Colin Mallory Series of Sliders fanfics. Although it takes place in the fifth season, the plot of the fanfics are similar to the plot of the first season episodes.

Newspaper Comics

Lord Amadeus's A Calvin for All Seasons manages to convey the heart of Calvin and Hobbes' friendship.

Video Games

The Ace Attorney sprite comic Kristoph Gavin Ace Attorney does a very good job of emulating the original's style.
The longer the Super Mario World romhacking scene sticks around, the more its participants rely on different graphics, new music, and unusual game mechanics in order to make their creations stand out from the pack. Return to Dinosaur Land, on the other hand, is a hack consisting almost entirely of levels that could have been in the original game.
- These sort of hacks are usually referred to as "vanilla" hacks by other members of the scene.
Screennameless's Gears of War fanfic Reconnoiter is praised for its borderline obsessive maintenance of the canon character's personalities even as new characters are introduced.
The whole purpose of the Tomb Raider Level Editor project Back to Basics 2009—all levels must be built with only the resources given when the editor was released to the public nine years ago.
Silent Hill: Promise attempts to faithfully create a full Silent Hill game as an interactive web comic.
Neutronium Dragon's Sojourn would make a dark (and relatively short) installment of Quest for Glory, but as a story, it would fit right in—out-of-left-field goofy moments included.
Til the Sun Grows Cold and the Stars Grow Old was written with this trope in mind; it was intended to be so close to canon that it could be read almost as a novelization of The Legend of Zelda: Twilight Princess.
Often cited as one of the main sources of appeal of the Ace Attorney Fan Fiction A Complete Turnabout, despite it being a Alternate Timeline Fanfic.
The Joy of Battle: Historical Espionage Action is a Metal Gear Solid 3: Snake Eater fanfic that presents the adventures of the Cobra Unit in a similar style to a Metal Gear game. The story does not change any of the existing canon and includes the Once Per Game torture scene as well as a prison escape, dramatic "ultimate weapon" reveal, and quirky villains. The main break from the style of the Metal Gear games is a non-linear plot.
Between Minds by 3theCaptain is one for the Half-Life and Portal universe. "If all goes according to plan, this story will not interfere at all with the canon material."
While a number of Pokémon hacks shoot for ambitious story telling, changes to the overall badge collecting formula, or otherwise veer off the main series's very narrow design concept, the Emerald and Fire Red hacks Altair, Sirius, and Vega are designed to mirror the main games in every way, from the stat spreads of their new Pokémon down to the style of music, trainers, and towns. About the only thing that's out of place from the typical games is the last of the three's extreme difficulty, and their choice of an eighth Gym Leader.

Web Comic

There are many, many Homestuck-derivative fanworks. However, probably the most Original Flavor of them all is Housetrapped, which carefully copies the art style of the original with different characters, and which is being used as the basis for a fan-game.

Western Animation

Avatar: The Last Airbender has Lost in Translation, which makes up a fairly realistic origin myth that all the four nations would know... and then creates a new version for the fire nation under Fire Lord Ozai's rule.
Some of the later works of JBERGES in the Futurama Fanfic community read exactly like a Canon episode, only with the science and math gags turned up to 11. Of Mice and Mensans^{[dead link]} is probably the best-written example, despite being Script Fic.
Though she dislikes being recognized for only this, The Illustrious Crackpot did one of the best Phineas and Ferb fanfics in the entire fandom: The Great Danville Cold Wars.
There are quite a few Powerpuff Girls fics written as if they were actual episodes.
Though it starts out roughly, The Clone Wars: Commando's Dirge winds up having several readers proclaiming it not only tastes just like Karen Traviss' Republic Commando series, it seamlessly brushes against a chapter of Triple Zero, without changing the scene at all.
- And without all the Jedi-bashing, too.
The Stepbrother Sitch (a Kim Possible and Phineas and Ferb Crossover written by "Owennumber1fan") and all its follow-up stories are as close to the shows as possible, with plenty of Lampshade Hanging, Continuity Nods,(possibly bordering on Continuity Porn at times) and some thoughts on various pieces of Canon Fodder.
Word of God from authors Kendell2 and Shadow Raikou says one of their main goals with the My Little Pony: Friendship Is Magic fic Getting Back on Your Hooves is to emulate the series itself. They've even stated that the events of the real episodes take place before, after, or, if at all possible, during the events of the fic.
Most Adventures of the Galaxy Rangers fanfics try for something close to this, but remove the 80's cartoon radar system.

Multiple

Author Umbra the Hedgehog seems to have a taste for Original Flavour. Aside from a few quirks, most of their stories are obvious (but apparently highly effective) attempts at writing things that might pass for actual episodes.