The mystic city of K’un-Lun is home to great warriors called the Iron Fist, a once-per-generation champion trained to best the dragon Shou-Lao the Undying to claim the mystical power within its heart. Over their long history, the Iron Fists sometimes journey to Earth for adventures and in modern times, those from Earth take up the mantle of the immortal weapon known as the Iron Fist.
Like Unto a Thing of Iron
The story of the Iron Fists begins roughly a million years ago when the extra-dimensional world known as K'un-Lun comes into being after a group of alien travelers become stranded there. Though they are able to begin building the main city with the remains of the ship, an explosion of the warp drive creates an oscillating connection to Earth, allowing the city to materialize in the Himalayas sporadically; though some have found alternate ways to travel between the two places. The aliens eventually make allies of the native Dragon Kings and develop their own monarch with Yu-Ti, the August Personage in Jade as the leader and Lei Kung, AKA Thunderer, as the main protector and master of the School of Thunder where students learn martial arts.
Due to the machinations of the time-traveling sorcerer Master Khan, the dragon Shou-Lao attacks Yu-Ti and is slain by Qu'an-Star who cut out the attacker's heart. However, Yu-Ti brings the dragon back to life and keeps his molten heart in a nearby cauldron, thus beginning a cycle of death, rebirth, and bestowing of power for the creature. A million years ago, a teenager named Fan Fei launches herself through the dragon in a rage and becomes the first Iron Fist, but she is quickly banished to Earth.
During a time of great unrest in K'un-Lun, a warrior named Quan Yaozu finds Shou-Lao and defeats him, becoming the first publicly celebrated Iron Fist. Others follow Quan's same path for becoming the Iron Fist many times over the centuries. Along the way K'un-Lun allies with the other Celestial Cities, each with their own Immortal Weapon defender. Every 88 years, the realms link up at the Heart of Heaven and they have a tournament to see which place can stay connected to Earth for a longer period of time.
Over time, more levels are added to the ritual. After a lifetime of training under the Thunderer, the young can test to see if they are worthy of becoming the Iron Fist. On their 16th birthday, they can attempt to snatch the crown off of the Serpent King's head. After further training, Yu-Ti sends the potentate against the dragon Shou-Lao. If they best the beast, they leave marked with the dragon's symbol and plunge their hands in the cauldron holding his molten heart.