Shadowmere
Even as a foal, following after her mother on long uncoordinated legs, she was the subject of derision they thought she couldn't comprehend, because no horse like her had ever been born in the Imperial stables before. Her ebony coat and more particularly her glowing eyes marked her out, and the grooms used to whisper that she had been touched by the Daedra - that Nocturnal herself, or Mephala, would one day come and claim her as a steed.
The one person in whom she found sympathy was an aged Dark Elf, ash-skinned and red-eyed like herself, who used to feed her sweetrolls and call her his little Dunmer filly. But he retired and went back to his Morrowind homeland, and all too soon her mother was with foal again. And when she was weaned, or rather dragged from her dam, neighing in anger and distress, she found herself alone. The other grooms kept up their cruel mockery, calling her demon-horse, and saying she was better suited to an Orcish dining-table than the Emperor's service. And she understood the tone of all this if not the words, and by the time she was a year old she trusted no-one, her innate spirit, soured by suspicion, manifesting itself as a savage temper and a readiness to bite and kick.
At the time all the other young horses were being assigned to soldiers and sent out on their first patrols, she was engaged in bitter daily battles with the stablehands. It was as much as they could do to strap on the saddle and force the hated cold metal into her mouth while she plunged and reared and struck, looking every inch the demon they said she was; not one of them dared mount her. Finally pronounced unhandleable, she was still a pure-bred with a lineage traceable all the way back to Tiber Septim's favourite charger, and therefore far too valuable to send for slaughter. So they turned her out into an empty paddock, her only companions the birds and an occasional curious deer. When other horses passed on patrol, she would rush to the fence and call to them, but none ever answered; they were far too well trained.
And there she stayed, until the day a man dressed all in black came to stand at her gate, and she, desperately lonely and recognising a colour like her own, went over to greet him. He laid long fingers against her forehead; he spoke soft enticing words to her, calling her his friend. And she stood quietly and listened, the attentive flickering of her ears her only movement, and by the time he had finished speaking she would have followed him anywhere.