As I said in my previous commentary, "Why Does the Captain N Fandom Continue to Survive?", fan fiction makes up the majority of the Captain N fandom. In this commentary, I'm going to discuss the many different ways that Captain N fan fiction is written.
1) The real characters fic
The cartoon series contains a lot of inaccuracies regarding video game characters. This annoys video game players, so they replace the cartoon versions of characters such as Mega Man, Kid Icarus, and Simon Belmont with the video game versions. This is usually done without any explanation for why the characters are suddenly different. This makes these fanfics alternate universe fics. It doesn't matter if they contain references to events in the cartoon series. They're still AU fics.
Example of this type of fanfic: Mandi Paugh's "Mega Man--The Series".
2) The major changes fic
A lot of fans find things in the cartoon series that they don't like: a character, a primary location, etc. So, they change things. Duke is often the first character to go. Old guys leave. New guys come in. The N Team might move to a new location or face a new villain. Even Kevin may be replaced by a new Captain N.
Example of this type of fanfic: my Captain N continuation (The "CHANGES" Miniseries, Seasons 4-8, Dazzle, etc.)
3) The modernization fic
As newer Nintendo consoles come out, fans want the N Team to experience modern games. So, they jump ahead to the Super NES era (which the cartoon series actually reached but, for some reason, decided to not acknowledge), the Nintendo 64 era, or the Gamecube era. Kevin's weapons are usually upgraded. This type is often combined with type 2.
Example of this type of fanfic: My "Captain N64" and, even though it doesn't jump ahead to the N64 era, "The N64 Team".
4) The true-to-the-show fic
There aren't many fanfics of this type. No changes are made to the situation in cartoon series. The N Team fights goes to an NES video game world and fights a villain, whether Mother Brain and/or her lackeys or someone else.
Example of this type of fanfic: seven7's "Jason and the Nintendonauts".
5) The comic book fic
These fanfics are based on the comic books instead of the cartoon series. I haven't seen any examples by other writers.
Example of this type of fanfic: MASK's "Captain N: The Game Master" and "The Legend of Zelda" titles.
6) The fusion fic
Writers blend the universes of the cartoon series and the comic books together and select what they want as canon, similar to what Dreamwave is doing with their "Transformers: Generation 1" comic book.
Example of this type of fanfic: I did see one on FanFiction.Net, but I forget what it's called and who it's by.
7) The crossover fic
Captain N meets characters from another TV series, comic book, movie, novel, etc.
Example of this type of fanfic: Jo Ann Montgomery's "Guardians of Videoland".
8) The fresh start fic
Fans might decide to toss the cartoon series out the window and start the story over again from scratch.
Example of this type of fanfic: Chris Blair's "The New Adventures of Captain N: The Game Master".
9) The self-insertion fic
The author writes himself or herself into the story and becomes the hero or at least a powerful ally. Commonly known as a "Mary Sue" fanfic.
10) The episode-based fic
A sequel or prequel to a cartoon episode.
Example of this type of fanfic: Aly Handman's "The First Videoland War".
Those are the main types of settings for Captain N fanfics. Now, I'll list ways that the fanfics can be written. These are more general concepts, so I won't give many examples.
1) Rewrite. Take a novelization of the show or the general plot of an episode and alter it to use new characters. Chris Blair is a master of this type of writing, and that's not a compliment.
2) Alter a script. Find a soap opera (or other) transcript and change the characters' names and locations. Instant Captain N fanfic. The drawbacks are that you'll usually get busted for plagiarism (except in the cases of soap operas, where readers will likely neither know nor care), and the characters will often behave out of character.
3) Insert Captain N into another author's video game fanfic.
4) Find a video game walk-through and novelize it, have Captain N quote from an instruction manual (which can be found online and pasted in) for instant backstory.
5) Have Kevin cross over to your favorite show, movie, comic book, novel, etc.
6) Make a good attempt at writing an original story. If you want to justify some things, make references to cartoon episodes and quote dialogue. It'll make it seem like your fanfic is a natural progression from the TV series. I did this in "CHANGES" and, to a lesser extent, my earlier fanfic episodes.
You don't even have to know anything about Captain N to write a Captain N fanfic.
Now, I'll list the common things that Captain N fans argue over regarding fanfics.
1) Rating. Should the story be rated G, be "family-friendly", and be "true to the show"? Should extra violence and swearing be allowed? Should R and even NC-17 fanfics be allowed for stories "based on a children's cartoon"? I say "Anything goes!"
2) Tastefulness. If there's sex, should it be handled "tastefully"? Should "third-rate smut" be banned? I say that sex scenes don't have to be written tastefully.
3) What exists in Videoland? Does blood exist? Some fans say no, but look at "The Lost City of Kongoland". Simon sees a red stain on his coat and exclaims "I've been hit!" Blood does indeed exist in Videoland. Don't be afraid to write about it. Do homosexuals exist in Videoland? Some fans say no. I have to address these questions, because, sadly, there are a lot of "Captain N purists" that are so closed-minded. Pathetic but true.
4) Accuracy. Captain N fans play video games. A lot of video game players are very picky about accuracy to the games and complain if the author gets something wrong. Of course, any knowledge of a video game would make a fanfic author more qualified to write a Captain N story than the actual TV writers, because they messed up not only the video games but sometimes contradicted facts about the cartoon characters themselves (not that there were many facts to contradict).
Now, with all that said, I say write whatever you want. There is a rich source of video games to choose from. There are over 500 video games for the Nintendo Entertainment System alone. That's a lot of potential Captain N fanfics, people. Get writing, and have fun!