Oh, here we are again, oh joy. I'm not sure why, but I was thinking about James Cameron's film Dances With Blue Hippie Cats, or Avatar for short. And then some recent reading involving the charming, decadent and utterly barbaric realm of Warhammer 40,000 AD decided to mess with things.
I believe that there are a number of crossovers, mostly along the lines of 'Imperium annexes Pandora' or suchlike. I don't think there's ones where the Na'vi are the Imperium… yet.
For Holy Mother
The ship that dropped out of the Warp above the fecund moon known as Pandora was, by most standards, a titanic monster: a thirty kilometres long, lightly scarred mass of armour festooned with a vast array of guns, missile racks, and the Imperial Torukh Makto on the prow, daring any despised Xenos to do their worst.
Aboard the Zamunge te Tistiä Na'vi, there was consternation. On the bridge – or if you were of the crew, tsenge te tsaheyl si tawsip – the captain's face drew into a scowl. That would be frightening enough, except that the captain was wearing full battle armour; as a tsamsiyu tsahik te Eywa, he preferred it. Not only his life, but body and soul were devoted to the protection of Holy Mother Eywa and her people. Especially his body. Most Na'vi felt a frisson of fear looking up at the bulkier giants of the warrior-shamans; more so when they were armoured.
"What madness is this?" the Captain growled, glaring at nothing except the visions the tsaheylu with the ship gave to him. "Where are Mother's Swords, Mother's Shields? Why have we not been hailed?"
The Listener replied with a quaver of fear. "Blessed Warrior-Shaman, the stars are right, the Sailors have brought us to Holy Mother Eywa… but…"
"But what? And spare me my titles. What has happened to Eywa?"
"It is as though there is no Imperium!" the Listener cried out in confusion. "There are no voices on the Imperial frequencies, no sign that Mother's Crown ever existed, nothing! It is as though we have been cast back in time!"
"Back in time?" the Captain gasped. "Before Mother's Awakening?" He'd heard tirol of the days before Eywa suddenly became more active, urging her children to learn new songs, new ways to hunt and mine and forge and live. Under Mother's guidance, the Na'vi had reached beyond their world, then to the stars…
…and they had found other beings, ones that lacked the ability or even the interest in bonding with their mothers. Disgusting blasphemies that crawled like devouring worms on the carcasses of their worlds.
Worse still, they sought to feast on other worlds as well. And they saw Mother as just another world to eat.
So there was war; war of extermination. War to protect and defend the Holy Mother, who had known about the threat that these Xenos posed all this time.
"Wait…"
The Captain turned his eyes to the bridge, a dull pod where the highest-ranking crew members communed with the ship's own Mother's Daughter. The Listener was looking pensive and alert.
"I hear something…"
"Daughter has seen something," the Watcher added, "It is like a wound on the Holy Mother… vä!"
"Vä!" The Listener added, eyes narrowed with disgust.
"What?" demanded the Captain.
The response was a flurry of epithets in angry Na'vi, neither of the two hearing him in their anger. He counted to ten, then reached over and deliberately yanked their queues, causing them to jerk and yelp and stare at him.
"What," the Captain rumbled ominously, "has happened to the Holy Mother?"
"Xenos," the Listener snarled at last, "Xenos defile Eywa."
I think you can see where this is going. One small mining colony, even with a General Quaritch, against a pack of augmented Na'vi who just happen to be heavily armed religious maniacs. Of course, you have to wonder what the native Na'vi will make of these newcomers as well…