The latest trailer for Iron Fist season 2 may well have revealed how the series could introduce more of the Immortal Weapons - champions of the Seven Capital Cities of Heaven. Although the trailer largely focused on action sequences and fights, it also dropped a few intriguing hints about the plot of this upcoming season.

A glimpse of a previous Iron Fist's body suggests that the show will explore the secret history of the Iron Fist. That's an exciting prospect; it suggests the series could draw inspiration from Ed Brubaker's Immortal Iron Fist run, in which he took a similar approach. One of Marvel's most creative writers, Brubaker penned a story in which he reinterpreted and extended the Iron Fist mythos, introducing a whole host of new characters as he did so.

Related: Why Iron Fist's Comic-Accurate Mask Looks So Weird

The most important of these characters were the warriors known as the Immortal Weapons. They've since become a vital part of Iron Fist's world in the comics, and fans of Iron Fist are eager to see them make their way into the Marvel Netflix shows. The trailer for season 2 may well have shown just how that could happen.

Who are the Immortal Weapons?

Iron Fist - Immortal Weapons

There are seven Immortal Weapons, and Iron Fist is one of them - the champion of K'un-Lun. We've also already met two other Immortal Weapons on the show: Danny Rand's old friend Davos a.k.a. Steel Serpent, who will be the main antagonist of season 2, and the Bride of Nine Spiders, who was played by Jane Kim in season 1 (though her character wasn't really explored in detail).

Attentive viewers will have noticed that, back in Iron Fist season 1, Danny referred to K'un-Lun as "one of the Seven Capital Cities of Heaven." These are ancient realms that are hidden from the eyes of normal men. Each is inspired by a different martial arts or fantasy trope: K'un-Zi, for example, is a city of Dark Magic, ruled by the sinister Crane Mother; Tiger Island is a tropical paradise where women are expected to cater to men's every whim; and the Kingdom of Spiders, sometimes called the Dark Kingdom, is a city in Nepal covered in spider-webs. Just as K'un-Lun is protected by the Iron Fist, each of the Seven Capital Cities of Heaven has a champion. Z'Gambo, in the darkest jungles of Africa, is guarded by the mysterious Prince of Orphans, the peaceful island of Peng Lai by the Fat Cobra, the Kingdom of Spiders by the Bride of Nine Spiders, Under City by "prankster-assassin" Dog Brother #1, and Tiger Island by femme fatale Tiger's Beautiful Daughter.

In the comics, Danny Rand only learned about the other Cities when a previous Iron Fist, Orson Randall, arrived in New York warning him of a coming battle. Danny soon discovered that, once every 88 years, the Seven Capital Cities of Heaven are merged into a single location known as the Heart of Heaven. The champions are then expected to fight one another in a brutal contest. The latest Tournament of the Heavenly Cities became a lot more more dangerous because Davos had persuaded the Crane Mother to make him the champion of K'un Zi - the Master of the Cranes. The Immortal Weapons were ultimately forced to work together against Davos, who had forged an alliance with Hydra in order to attack the Heart of Heaven.

The Immortal Weapons have become an established part of Iron Fist lore since their introduction in 2008, but in the TV show neither the Bride of Nine Spiders (who appeared to simply be an agent of the Hand) or Steel Serpent have been established as Immortal Weapons in their own right. However, the recent trailer has us speculating that Iron Fist season 2 will dig deeper into the history of the mystical cities and their champions - and there could be more to New York than meets the eye.

Page 2: How Marvel Could Introduce the Immortal Weapons

Finn Jones as Danny Rand in Iron Fist Season 2

Iron Fist Season 2 Introduces Previous New York Protectors

It wouldn't be hard for the MCU to rewrite Orson Randall as the last champion of New York, and New York itself as the site of one of the Capital Cities of Heaven. The trailer for Iron Fist season 2 includes an intriguing scene in which Danny and Colleen are exploring the sewers beneath New York City, and stumble upon a skeleton bearing a mask that will be familiar to any reader of the comics: the traditional mask of an Iron Fist. The clear implication is that Danny Rand is not the first Iron Fist to battle in New York, and indeed that one of his predecessors died in the city's defense. Orson Randall's father was a genius whose work had been lost in the sewers of New York, and in the comics Randall died there in a battle against Hydra.

But just what is the connection between the Iron Fists and New York City? There has been one intriguing clue: in The Defenders, we learned that dragon bones lie beneath New York. Perhaps New York was once home to a city similar to K'un-Lun, with another dragon at the heart of it - and presumably an Immortal Weapon akin to the Iron Fist. When the dragon(s) finally died, the order of New York would have been rendered powerless, unable to continue the line of Immortal Weapons.

Fans have theorized that recurring villain Madame Gao could actually be the Crane Mother, the leader of K'un-Zi, and Gao was seen at the end of Iron Fist season 1, eavesdropping on Davos' conversation with Joy Meachum. Gao was caught in a collapsing building in The Defenders finale, but we wouldn't put it past her to have escaped and started plotting with Davos to bring down Danny Rand once and for all. If Gao really is the Crane Mother, then perhaps she will appoint the Steel Serpent as her champion - just as she did in the comics.

Related: Iron Fist Season 2 May Be Retconning Danny's Origin Story

How Marvel Could Introduce the Immortal Weapons

If this theory is correct, Marvel is building up to the introduction of the Immortal Weapons. Season 1 name-dropped the Seven Capital Cities of Heaven, while season 2 appears to be introducing the legacy of Orson Randall, the man who taught Iron Fist about them in the comics. More than that, though, this idea may explain just how the Immortal Weapons work in the MCU. If there have been other ancient cities like K'un-Lun, hidden realms that are home to a dragon and defended by champions, who's to say they have all been destroyed? These last handful of dragons could have been kept safe from the Hand because, like K'un-Lun, they existed in other dimensions that only intersected with our own reality at occasional intervals. They, too, could have defenders who had been empowered after an encounter with their city's champion, and who gave their lives to defend their homes from the Hand. That would provide a simple origin story for the Immortal Weapons in the Marvel Netflix shows.

Brubaker's run is one of the most important in the history of Iron Fist, and the first season drew loose inspiration from it. That pattern appears to be continuing into season 2, and it would make sense for Marvel to continue that. It's unlikely the other Immortal Weapons will be introduced in season 2 (it would have been difficult to keep that kind of casting news a secret), but it could well lay the foundations for their arrival in the next season. Perhaps we could even get a season 3 inspired by Brubaker's Tournament of the Heavenly Cities, with Danny forced to battle against the champions of the other cities.

More: Iron Fist Season 2: Every Update You Need To Know

Iron Fist season 2 premieres Friday, September 7 on Netflix.