Even before the fall Ruby Heart the white furred Earth pony had lived with Steel horn the Unicorn, ever since he found her wounded and alone in the wilds surrounding Canterlot. He took her back to his family home and cared for her, nursed her back to health and the two have been inseparable since then.
After the fall Steel Horn took ownership of Ruby along with the mares in his family so he could do his best to protect them in this dangerous new world they found themselves in.
Steel didnt seem to change that much after the fall, still putting the care of the fillys he owned before his own needs, and Ruby loved him for it. She enjoyed taking walks with him in the forest whenever they could get away from the city for a little while.
Her hand in his as they cuddle beside their favourite tree, It was almost as if things were back to the way they had been before, she wished she could stay there with him by the lake forever. But eventually they would have to get up and return to Canterlot once again. Moments like this though gave her the strength to keep going.