Geometric bear on upper arm

There was a winter the Ouse froze so hard the lock-keepers walked out to the middle and played cards on the ice. A carpenter's widow named Hester Pell kept a cutter moored below the bridge, and on the coldest night of that year she heard something big breathing on the towpath. She didn't light a lamp. She knew better. She went out with a loaf and her bread knife, and found a bear no one had brought over from anywhere, its coat all corners, grey as slate where the moon hit it and blue where the frost had got under the fur.

It wouldn't come near the bread. It walked the towpath back and forth, angling its great head at the water, at the boats, at her. Every time it turned, it turned sharp, like a thing made of folded paper, and every fold caught the light a different shade. Hester thought it was lost. Then she saw the front paws had gone blue to the ankle where the river had soaked them, and she understood it was trying to reach the water to drink, and the bank had iced over.

She cracked the ice with the bread knife. Nothing more to it than that. The bear drank, lifted its head, and walked off the way it came, sharpening itself into the dark until only the teal of its muzzle was left, and then nothing.

Hester kept the knife. She said that was the whole of the bargain, and the bear had paid it in corners.