True Companions/Fan Works

Examples of True Companions in Fanfic.

The pack in the Canisp series. None of them are related (except for a pair of sisters), but Meya and Canisp consistently refer to each other as "sisters". When one of the group makes a mistake that nearly kills them all and lands one of them with a broken leg and a concussion, they all stand up for him against the rest of the Wolves, insisting that it was an honest mistake and he learned from it--this in spite of the fact that one of the group spends most of her time glaring at him.
Dumbledore's Army, in Dumbledores Army and The Year of Darkness, are definitely true companions long before the end of the story.
The Chance Encounter crew. Strange, dysfunctional and prone to good natured bickering, they have literally gone through hell for one of their friends.
The SOS Brigade has become this even more in Kyon: Big Damn Hero, so much so that Kyon referred to all seven of them as "nakama" whilst recovering from being shot.
The entire point of "circles" in the Ouran High School Host Club fanfic In The Circle of Elemental Arms.
Explored beautifully in the Cowboy Bebop fic Freaks Flock Together.
The League of Extraordinary Gentlemen (and Elizabeth) in The Private Diary of Elizabeth Quatermain.
The main characters of Chance Encounter, all of whom are, to one level or another Deadpan Snarkers and all completely loyal to one another.
The Dangerverse, in all its iterations, practically runs on this trope.
In stark contrast to the original, Shinji, Rei, and Asuka in Shinji and Warhammer 40 K are definitely this trope. They may have others that are close to them, they may view every human as someone to protect, but their role as Pilots has created a bond that no-one else shares. Mana even expresses frustration at how improbable it is that she will ever be a part of it, but is content that her role results in her being closer to them than anyone else.
Team Free Will, in the Supernatural/Good Omens crossover Arrangements, which includes Dean, Sam, Castiel, Gabriel, Bobby, Aziraphale, and Crowley. As time goes on, it becomes more and more clear just how much they mean to each other, even if they have to pound it into each other's heads sometimes.
Remaining consistent with the original series, A:TLAR's Team Avatar never leaves a member behind, (except for that one time...) and every one of them will fight and die alongside the others, proud to have known such great warriors. However, they can be considered closer to Fire-Forged Friends than the original, due to the general hostilities between members. As time goes by, they will surpass numerous conflicts, including Katara and Aang's feud, Sokka and Suki's brief falling out, and Zuko and Iroh's temporary split from the team during Books Two and Three.
The group that Grumman refers to as "the allies," in the Elemental Chess Trilogy, are a very tight-knit crew who will not tolerate any harm coming to its members.
Hunting the Unicorn: The Warblers are Blaine's Crazy Prepared, Serious Business-conducting companions. Among being Kurt/Blaine shippers, several of them literally drag Blaine to counseling. And when they find out that Blaine has a stalker, they refuse to leave him alone.
- In the nineteenth chapter, it pays off like you wouldn't believe.
The Light in the Darkness shows Pinkie Pie and Rainbow Dash this way. The portrayal of the two is considered one of the best in the fandom.
- The Mirage squadron. Firefly even openly states that Rainbow is lucky to have friends like Applejack or the fellow pegasi flyers.
The four in With Strings Attached, and also in real life, at least for a while. In Strings, they have to stick together, since they cannot trust anyone else.
- Despite being Actual Pacifists, all of them have Berserk Buttons if one of the others is threatened, and will attack immediately, albeit nonlethally.
The Malificent 11 from the Daria series God Save The Esteem will beat the hell out of each other on an hourly basis, but Heaven help you if you look at (or near) any of them even slightly askew.
The main group from Calvin and Hobbes: The Series: though they're dysfunctional, they'll (mostly) always stick together.
Clan Gully from The Tainted Grimoire.