Story inspired by UTOverse, created by  Sarya
Character courtesy of  Lasket

"HC" or "Human Coalition" is an organization founded after the war for Earth. Combining most of the Earths nations in to a single union for ease of communication and decision making.
The "HIRA" units are autonomous or piloted mechanized multipurpose machines. "HIRA" stands for "Human Interaction Robotic Assistant"
Such mechanized units are considered dangerous and illegal, possessing their own intelligence which is outlawed, unless used in very specific circumstances.
But nobody wants to try and go against the "UHF", which seems to be what the machines call themselves. "UHF" stands for "United Human Force". Though many call them "Unknown Human Force".
While it is not known where these machines came from, their purpose is known, to protect humanity, with most of their technology heavily based of human equipment, even going as far as using human markings and terminology.
It is speculated that these machines were created by an artifact known as "The Construct". Ancient super computer with near limitless capabilities. How, why and when it fell in to humanity's control is not know. It is not known who controls it. Unless it acts out of it's own free will.
Currently, UHF is being treated as a PMC, rather than a proper human army, UHF will only provide their strength in time of need. The Human Coalition has no power over UHF.
*Note that the unit on the left was modified to appear more friendly to the locals while still being able to operate normally, performing various tasks.

"War for Earth"
The war began out of a series of terrible mistakes made by both sides of the conflict, over aggressive reaction from humanity and terrible decision making by the "DR" or "Dastal Republic".
Thus began the 14 day siege of Earth, which ended in a devastating loss for the Dastal Republic, not expecting humanity to posses such unique ways of waging war, they received a fatal blow to their orbital defenses, breaking the blockade and allowing a different space alliance to take the initiative.
While an average human is nearly 10 times smaller than the average alien, humanity went the path of kinetic weaponry, which while complicated and required a massive amounts of logistics, proved to be very potent at taking down nearly anything the aliens threw at them.
But humanity lost a lot more than they've gained, loosing many people in the war, not even mentioning the terrible atrocities committed by the invaders, breaking humanity's will to go on.
Earth was left devastated and vulnerable, left with no other choice but to be accepted in to the "SAT" or "Solar Alliances Treaty". The SAT is a vast alliance of multiple species which came to aid the humanity in their fight for survival.
Not being treated with respect humanity felt like they simply didn't belong in this universe, being as the only species with a sun that couldn't posses a certain type of energy.
Although after a year, things have improved ever so slightly, as a certain project began, allowing humans to pilot fighting machines. But that left many people wondering if humans are just used as "legal computers" for alien war machines.

"Post war situation"
Over a year after the war, humanity is being slowly integrated in to a new society, but many difficulties are in the way, proving to be a serious challenge to overcome.
Main issue being the sheer difference in size. Humans are unable to walk among the aliens and building a few billion mechs would be nearly impossible.
State of the art machines are only currently being tested by the military, thus very few humans could potentially set foot on an alien world.
But the efforts are not going in vain, potential ideas of building human only areas are being planned but that raises a question, wouldn't that be considered segregation?
The Earth is still left devastated after the war, many people lost everything they've had, their families, homes, jobs. And yet it seems like the governments are more interested in sending in their war torn soldiers back on the frontline, to fight for a new ideology.
Refusing to accept alien help in fear of crashing the economy, people are left with no choice but to rebel. Multiple conflicts sparked around Earth, as humanity began fighting itself again. In an effort to cull the violence, the aliens sent their peacekeeping forces.
With the arrival of the peacekeeping forces, the UHF responded with their own forces being deployed on Earth.