"We're all alien to one another."
Often alien races typically tolerated one another, but they were always separate. If they lived together, it was with barely disguised hate. "Live and let live, we're all better off if we keep to ourselves and stay apart. It's not natural to be with anyone other than our own kind."
That was the way it was until the humans came. See, most people didn't let alien refugees in; or rather they did, but never like the humans did.
When the humans first started setting up outposts and colonies, there was a rush of new business to their worlds. And of course, a rush of people trying to escape various disputes. The most famous case was when a human bureaucrat saw a group of refugee Arcturans, escaping prosecution in their own nation, approaching their embassy. The diplomat groaned in annoyance. "Fuck me, more paperwork."
The refugees were nervous, "We'll fill out whatever alien releases there are. We know how this works. I know we're not human, but please, help us!"
"What does being human have to do with it? I fucking hate paperwork!"
To their surprise, the refugees didn't have to wait for special permission, or for the embassy to make a federal case out of asking for asylum. They simply... let them in, the same way they would provide asylum to anyone of their own species. It was at a snails pace of course, but that was FTL compared to the standard.
They settled on a human colony, among the humans themselves. They didn't care that they looked like spiders, the humans just wanted them to pay their taxes and live like any other citizens. They were given special status as refugees. Another bureaucrat across the desk sighed, "Alright, fill out these forms."
"But... these are for humans."
"Look, the ink doesn't care who holds it! Just fill it out!" The bureaucrat had more paperwork to fill out. He hoped there was still pizza left in the break room.
The Arcturus refugee crisis didn't even reach their parliament until they formally asked for aid. "The chair recognizes the motion to provide aid to the Arcturan refugees, and to put diplomatic pressure on their government immediately for the mistreatment of these refugees."
An alien reporter asked one of their ministers if there was anything to do about the refugees. "What do you mean? They sought asylum."
"Yes, but they're not human."
"So?"
The galactic community quickly learned that while individual humans might have their biases, and some groups could be xenophobic, humans approached things differently. Their bureaucracies weren't based in species. To the beancounters, aliens were another hassle, simply more people to deal with. They weren't an earth shattering revelation to the bureaucracy. To the humans, the aliens were simply an annoyance in the same way any new country was. To the bean counting humans, nothing mattered about if the entity across from them had a claw, a gripper, or a hand. "Are you cognizant of what you are doing? Fill out the damn paperwork!"
They had no unique forms, no new statuses applied to aliens. They didn't form committees to fix all their laws for aliens. They formed them to adjust when necessary, when legal precedent came by. The humans were slow to change, but not resistant.
They acted as if their world hadn't been changed by first contact. It was simply another part of life to them. When the Arcturans were at that embassy so long ago, seated in a waiting room protected by soldiers, to their surprise, they were shocked by what human news was saying. "Our top story today: a shipping accident at Tau Ceti has caused a shortage in quantum computing chips..."
The Arcturan refugees remained in human space. Then, one of them gave birth. Surely the aliens thought, this would cause a diplomatic crisis.
Indeed, a federal agent appeared when notified... to ask them to fill out birth certificates and other information. She was surprised at the Arcturan confusion, "The kid was born in one of our hospitals, right?"
The various alien species wouldn't live together deliberately, or in large populations. And none allowed birthright citizenship. Yet within five years, there were dozens of Arcturan Earth Alliance citizens.
Soon though, the ones the Arcturans had been fleeing came along. A group of pirates, led by a nasty piece of work, Colonel Piowho formerly of the Arachnid Special Forces. All evidence suggests he never did stop working for them, he was plausible deniability. He appeared above the human colony where the majority of the Arcturans were settled. "Hand those scum over! They're to be brought back to our space!"
"This is Earth Alliance Station Melos. You are intruding in Earth space. Leave immediately."
"Those are our citizens! Give them up!" Piowho snapped. "They are escaped criminals. They all deserve to die! We are formally extraditing them!"
"If you wish to submit a formal inquiry, then do so. Immediately deactivate your weapons and proceed to the nearest federal outpost."
The space station was struck by a volley of missiles. The Aegan system became a battle ground, between the pirate ships and settlement defenses. It took days for an Earth Alliance fleet to arrive. When they did, it was a mop up operation. The colonel himself inflicted the biggest loss, doing what they called a kamikaze run on an Earth Alliance frigate. The colony was battered, but the humans had fought hard, and won.
To the Arcturan's shock, there were no federal reprisals against them, no attempt to extradite them. Any humans who inflicted harm on them was judged and sentenced with hate crimes.
In the galaxy most saw rules of war applied to their own species and frequently would justify their own war crimes by claiming theirs didn't apply to extraterrestrials. But the humans saw it differently. "Crimes against humanity" was a philosophical designation, for the act of being humane, it did not refer to the species. Few, if any, races let any aliens enlist in their armies either.
When more pirate raids came, the humans launched a full scale assault on their main base. The human fleets were still so new to the galaxy, yet among their ranks were humans and Arcturans, eager for revenge and a desire to help their new friends. The Earth Alliance took deep losses, but the pirates were completely wiped out. Human and Arcturan slaves alike, along with slaves of a dozen other races were rescued.
The Arcturan community grew. Many human veterans joined them, proud to live with their newfound friends. The first marriage between a human and an arcturan took place merely a month after the Big Raid. And three Arcturan families adopted human children orphaned by the slavers.
There was one other thing the humans did that stood out. They built communities. When aliens built settlements, they would be populated with only their own people. The Bull folk would populate a space station with their own, the Cetians would fill a settlement with theirs. they designed them with their own people in mind. They would accommodate others, but assumed they would keep to themselves. No one integrated on this level!
Then came the infamous meeting.
On hearing of the marriage, and the adoptions, a member of the galactic council, the Cetian ambassador, snarled in disgust, "We must remain pure. We cannot mix together! It's better if we live with our own kind!"
The humans saw it differently. "We're all alien to one another," their diplomat said, "Even between members of the same species."
The councilman scoffed, "If that is true, then all the more reason to stay segregated. Mixed communities lead to nothing but disaster."
"With all due respect, ambassador, we've heard such things before." the human had a cool expression. "And I hardly think my adoptive daughter is going to kill me in my sleep."
The councilman choked, "You mean... you adopted one?!"
"We're all alien to one another, councilman," the human growled.