Disclaimer: I do not own Avatar, nor would I ever claim that. So, if you see something in here that you know from the movie or the game, its probably not mine.
Well, this is my first story... So be nice, etc., etc. If you find any mistakes, please do point them out to me.
A few years after the Great Battle and the following eviction of all RDA personnel, rumors were heard about a sky-person in the jungle. It was said that he was clad in plants and very stealthy even in comparison to skilled Na'vi hunters. They were at first disregarded, until the day on which a hunting party came too late to rescue a small group of playing children from a raging palulukan.
They could only watch, at first in terror, then surprise and wonder, as a part of the underbrush stood up, assumed a humanoid shape and defended the children. It had about the height of a sky-person, but its form was composed of bark and leaves. It shot spikes and whirled about the large predator until he retreated. Only a scant few of the spikes had missed and the being had acted in complete silence. Over the roars of the palulukan, only a slight rustling of leaves and the whizzing of the flying spikes had been audible. Afterwards, it gave a small bow in the direction of the still-concealed hunting party, a wave and a smile with a bark-covered face to the children and vanished between the trees.
Although they tried, they couldn't find any trace of it on later days, but the remaining spikes and the tracks of the large palulukan served as evidence of the incident.
Half a year later, a child that had been missing for days showed up at her clans Hometree and told her story of getting lost after a nasty fall from a cliff and being shown the way back by 'a wandering bush'.
Over time, several clans began to tell stories of similar incidents where a well-concealed stranger either saved single members or, in rare occurrences, a larger group from mortal danger. The 'fnu tirea' or 'silent spirit', as the being became known, never lingered where it was seen. It never talked, but was always polite in giving a wave or bow before vanishing once again.