A rustle in the grass
It grew as it tread. Nature produced a force and nature itself was drawn to it. It thrived among the surroundings of its lifeless kin. Leaves were attracted to it, branches bent towards it. Everywhere it went life flourished and grew with a greater vigour. It was a way for nature to feed itself, to regenerate itself. Other sentient beings chose to tear down its towering trees and gouge out the seeds of the earth in favour of structures of stone and iron. At some point enough was enough. Nature’s energy organically rose up to protect and deter.
It had no means of communication. It just responded to interactions from other sentient beings. Interactions that usually were hostile. Hostility is answered with a display of primeval force. It growled as it pushed aside a branch and detected one of the Elves that had followed it around for hours. Arrow after arrow had pierced his hide. Surely this little one would understand now that Nature will always prevail.