I got an idea for a Avatar au
So'lek and the Tamtey find a portal to Earth in a old RDA base. But it wasn't made with human technology, it was designed by ancient Na'vi. On the other side is a RDA facility on Earth filled with all kinds of secrets and plans for Pandora.
They run into humans but they are not with the RDA, they are international detectives investigating the RDA.
They learn that the people on Earth didn't know there was life let alone people on Pandora. The RDA was using the facility to alter the memories of everyone they deployed there so they can get away with their crimes. So they accidentally take down the RDA while looking for scrap tech. Earth's world leaders pretty much declare war on the RDA and are trying to get in the good graces of the Na'vi as they can show them how to avoid the mistakes that put the RDA in power. This means that Mercer is rolling in his grave as the Sarentu are actively making sure humans and Na'vi are getting along rather than getting the Na'vi to do whatever the RDA wants. The resistance becomes the head of diplomatic affairs of Pandora as they already have humans and Na'vi living together peacefully.
80sThe Mangkwan clan including Lyle and Quaritch go back to the ash lands after Bridgehead is taken over by the resistance.
So they follow and discover that the Mangkwan spirit tree is still alive. Thinking that Varang was hiding it from the clan to stay in power and keep the raids going but it turns out she had no idea. This results in her having a breakdown over all the pain and death throughout the years that she thought was necessary to keep her clan alive that turned out to have been avoidable.
This results in an awkward alliance with the Mangkwan, with Quaritch being leader while Varang is looking for her sister to reconcile with her.
Meanwhile the Sullys are suspicious of him so they are keeping a close eye on him while the Mangkwan are learning how to live in balance again in their own way with the Sarentu clan and the Uk clan (my fanclan). These three clan interact with humans the most as they don't mind using technology and most of the other clans are still wary of humans. Teylan falls in love with a Mangkwan hunter.
Once the last of the RDA is taken care of Earth's world leaders and the clans start to discuss diplomatic relations.
The resistance converts Bridgehead into a university where humans learn about Pandora and the Na'vi way of life to take that knowledge back in order to heal the Earth. Pryia teaches botany there while Anqa teaches pilots how to fly on Pandora without disturbing the local wildlife aka making sure a stormglider or toruk doesn't take a bite out of them. There is a carpentry class in honor of Jin and a veterinary class specializing in Pandora's wildlife in honor of Hajir. Seeds are planted wherever they can go on the university and totems are built representing each clan that visits, a tradition started by Tamtey. The students choose a clan to live with to learn their ways for a year after passing the Na'vi language course similar to the Sarentu. Instead of piloting avatars the humans have special implants that allow them to breath the air, eat the food, and bond with animals the same way Na'vi do.