They are, in fact, based on the Three. The very symbol of their clan is an iron, guantleted fist crushing a heart and making it an unrecognizable mass of blood. They see their cause as to crush the Heartland and squeeze the blood from it, squeeze the Faith of Life from it.
The Iron Fists are devout to the Three, but also oppose Terra. They do not want to submit to Terra but to conquer and dominate Heartland and invade Terra, expanding their influence. The current leader of the Iron Fists is known as the Iron Mask. No one knows if he is the founder of the Fists, or if the identity of the Iron Mask is passed on from man to man.
The Iron Fists is the third most populous clan in Heartland, but also has agents in Terra. They have the best armed and armored warriors of the bandit clans in Heartland.
Their main camp is a cave system in the forest south of Heartland City, but also have The Hidden Cathedral located under the streets of Heartland City itself from where the Iron Mask oversees his people.
No one knows his true name or motives but his men show him loyalty boarding on fanaticism. He is a follower of the Three and refers to himself as the 'True Patriarch of the Three' and looks forwards to the time he can slay Jodah the Father. He preaches his faith and sends preachers to do the same across the land, seeking to convert the people of Heartland before issuing his conquest. He also has people move into the Black Moon Raiders and (Less successfully) the Silver Winds to not only spy but to plant the seeds of the Three into both bands.
He tolerates no questions to his authority, and those who he sees as sinners and blasphemers are to be hanged. He maintains a growing list of people that are 'enemies of the faith' to have murdered with bounties on each.
A master of a battleaxe and a master of shadow magic, he's as deadly as anyone in Heartland.
The Phalcity family has been counts and countesses of Goldenport since before the failed Terran invasion. However Jamie's grandfather picked up a copy 'The Way of the Three' from a smuggler. Over the course of a year he read and began to convert to the Three. While he kept it secretive he started to apply more and more of the teachings to his life. Somehow he was contacted by the Iron Fists. Seeing the like minded individuals he started to find ways to funnel funds to them.
Today Jamie is as much of a follower as any Iron Fist and maintains a shrine to them under his manor. He is the main financial backer of the clan and uses his connections to find guard captains more willing to look away when the Iron Fists are involved. One notable moment had his guards arrest the local thieves guild, stash the seized loot in an undermanned warehouse which was then robbed by the Iron Fists thanks in part to a tunnel dug years ago by a smuggler.
Arrogant and haughty, but smart enough to mask it, he looks forwards to the day his family are masters of Heartland's east.
Dominic, as an impoverished child, found a book 'The Way of the Three' on a dead man. He hoped to sell it, but one of the local priestesses considered it an 'unholy' book. Curious he opened the pages and read.
As he learned and learned he became convinced that the Faith of Life feared the Three Sacred Lords of Heaven because their way was better and more rewarding. Life asked for sacrifice and generosity and understanding, but what about those who had nothing left to forfeit, little to give or were misunderstood?
At age fourteen he found a group of Iron Fist bandits beating a man in an alley while reciting the Way of the Three. He approached them, one of the bandits about to hit him before he recited a verse.
"Let the weak bleed and make them bleed. If they stand once more they deserve life. If they never rise again then only death should be their reward."
Impressed the man recruited the young Dominic to the Iron Fists and found he had an ability for shadow magic. Training under the clan he became one of the most devoted members of their order. Today he preaches to new disciples and recites the Way of the Three to a mass each Sunday.
Some consider him second only to the Iron Mask in leadership... And that he may take up that mantle someday.