The Immaculate Ermine

Within the snowy expanse of Sudland, many small mammalian creatures can be found, mink, stoals, foxes and rodents, but none are quite as rare or valuable as the immaculate Ermine. In days past, the irmine was believed to be spirits of the woods, darting behind trees and into banks, brilliant white even against the snow. Their fur shines in the moonlight, and their eyes seem to glow with a faint aura.
It was their beauty which first drew the hunters and poachers to capture them for their pelts, and their numbers rapidly declined. By a stroke of luck one such hunter captured an Ermine intending to skin it when he was home and warm, but it wasn't until he returned to his cabin that he noticed their most startling feature. As soon as he entered the warmth of the cabin the ermine leapt, breaking through the wooden bars of its prison and running straight into the fireplace.
The hunter started, trying to prevent the ermine from being harmed by the flames, when he stopped. Slowly at first, then rapidly spreading, the fur of the ermine changed from milky white to a fiery red. Thinking that this must be some trick of his tired eyes, the hunter threw a pot of water onto the fire, immediately dousing the flames. When he peered in, the Ermine was sat among the smouldering logs, now a shade of rippling turquoise. When he went to pick up the animal, it slipped through his fingers like oil, and dashed under the bed.
After many days of feeding and coaxing, the hunter befriended the ermine, and eventually divined its secrets. The immaculate ermine can absorb and project the elements around it, taking on some of their characteristics. This alone would be enough to make it a worthy pet to any lord or ruler, but the ermine had yet another use. When confronted with poisons, venoms or toxins, the ermine becomes a startling shade of green, and hisses angrily at the offending object. Thus is it the perfect tool for the hated, or paranoid, individual with enough money to afford such a rare creature.