Let’s tell The Expanse story from the POV of Mars and the MCRN. They get totally shat on this entire story.
They’re chilling, doing their own thing, and then this random ass little ice hauler shuttle broadcasts to everyone, saying that Mars blew up their ship. From Mars’s perspective, they’re like “??? What? No we didn’t. What the F?”
So they go and save this stupid little shuttle who is broadcasting a distress signal and accusing them of murder. Fine. Whatever. They’ll get to the bottom of this.
They think the OPA did it, and what do you know, there’s a suspected OPA operative in Naomi Ngata on board. So they start investigating, interrogating. As far as actual interrogations go, they treat their prisoners excessively well. No torture (remember the gravity torture back on Earth with Avasarala???). Just piercing questions and paying attention.
BUT WAIT. THERE’S MORE. Stupid mystery ships attack and BLOW UP THEIR FLAGSHIP. All Martian hands lost. Hundreds, if not thousands of lives.
The Captain basically risks everything to try to buy time to launch one of their Corvettes in order to clear the air. The entire escort contingent of MCRN marines dies getting Holden, Naomi, Amos, and Alex to the Tachi. They’re supposed to go to Mars and tell them the story, clear the name of the Donnager and Mars.
Let’s just gloss over the fact that Holden basically trades MCRN lives for the lives of Naomi, Amos, and Alex since he refuses to be transported without them, endangering EVERYONE.
But what do these jerks do? They claim the Tachi as legitimate salvage, rename the ship the Rocinate and FLY OFF BY THEMSELVES. Thieves!
But wait, there’s more! Earth, full of a bunch of untrustworthy jerks, tricks the Martian ambassador into revealing the site of all of their stealth production facilities, compromising their military position. On top of that, Earth MURDERS HIM! Fuuuuuuuu.
And for what? Mars didn’t do anything wrong in all this! They were just chilling, minding their own business, arguably doing the right things and then…BAM, kicked in the nuts over and over.
MCRN for life.
(but wait, there’s more… BOOK SPOILERS AHEAD)
They have to fight Holden and Avasarala’s war, losing two ships in the process, even in victory. And then when they go to take out the facility housing the Protomolecule monsters, A BAJILLION MISSILES CONTAINING THOSE MONSTERS GET LAUNCHED FOR MARS, THREATENING THE ENTIRE PLANET’S POPULATION.
And then on top of that, they get TOTALLY OWNED by the discovery of the gates. Their entire purpose of being goes away since nobody wants to terraform Mars anymore when they can just go to other planets. Their society basically crumbles, and lots of their weapons/ships go unaccounted for.
And what seems like half their fleet goes AWOL burning for the rings. They have no discipline in their military ranks anymore since their fleet won’t listen to their prime minister. AND THEN THOSE IDIOTS GO AND GET THEMSELVES KILLED BY MYSTERY ALIENS IN ONE OF THE RINGS.
So here’s Mars. Society on collapse, with an impotent military, a governing body that seems to have no respect, and a population problem because nobody wants to stay. A ragtag bunch of terrorists calling themselves “The Free Navy” have now confined them planetside on a planet that can’t independently support life. Fuck their lives.
tl;dr Poor Mars. They’re just sitting there, minding their own business and then BAM, everything blows up in their face.