Being one of the only countries to actually send ships to Mars on a semi-regular basis, the European Union found itself on the cutting edge of the new craze. With the ESA cashing in the profits of the gold-rush, with tickets to Mars all booked out almost upon their release and a huge demand for their transport services back home, travel became affordable to a lot of people. Even though there was an official UN body assigned to take care of Mars and administer it, it had virtually no power. The ESA on the other hand, holding the only space-port on the planet, soon found themselves as the de-fact governors of the planet and as such used their extraordinary new influence to push all the players around. But while they did that, they also had an even more profitable job on the side, smuggling. With the influx of people, the Mars-Express became the prime choice when it came to moving goods, that meant that some "economically savvy" Europeans were quick to seize the opportunity to transport goods that are illegal in other circumstances and cash in.
As was expected, the Mars-Express and the ESA were more interested in what went into their pockets, then what happened in Mars itself, and while they applied pressure everywhere to get their own preferential rights, they generally didn't care about who came to Mars. Soon enough, Mars became a center for dissidents, adventurers and misfits, people from all over the world flocked to the planet, with many countries establishing colonies in the vicinity of New Europa, the ESA's own center.
And with that, the conflicts came, first were the international conflicts, as order was quickly collapsing on earth, the major powers transferred their conflicts to the colonies, with the European Union and the North American Union's battling for dominance over the colony, the Chinese establishing bases for their corporate interests, racing with the Russians for more privileges , with the latter establishing the biggest mine on the planet, where people work in near-slave labor.
Next came the revolutionaries, escaping Russians, Britons and all sorts of unhappy folk found home in the mountains above the mines, the barely-passable terrain making it hard for anyone to hunt them down. They wage guerrilla war, but are not the only ones in this endeavor, as the Islamists on earthy (besides former Persia) gradually lost steam, they resurfaced in Mars, coming both directly from the arrival shuttles in earth and the local Muslim settlements, they operate all over the place but are concentrated in the mountains above the chief Arab/Muslim settlement.
Then came the banditry, with the gradual breakdown in order, the north became a haven for all sorts of thugs and low-lives. The city of Unity, the former UN seat on the planet, abandoned by all powers, became a hive of thuggery, barbarism and all sorts of criminal excesses one can think of. In the far north, Christian "crusaders" settled, and even further north, bandits roam the wastes in the north.
And then came the paranoia, with the gradual breakdown of peace, people fear for their lives. But there is something more sinister going on, the "Dusters", coming form the wastes, these raving humans seemingly lost all of their humanity, raid, pillage and burn, kill and main people. With the "Outliers" in the furthest south holding them back, they have been returning every season to raid, murder and kill, rape and pillage. They seem unstoppable, those who see them speak of flayed skin all over their bodies, their lips thorn from their face, exposing their monstrous teeth. They seem human in name only.
But aside from that, Mars is dandy, come visit us sometime.