Dinner is an assumed-to-be-male fox, who was animus-touched by the NightWing Stonemover. The dragon enchanted the fox to bring him food every few days. Stonemover referred to Dinner as a "he", but Dinner's true gender is still unconfirmed.
Once Stonemover began gradually turning to stone because of his spells, he enchanted Dinner to bring him food every few days so that he would not starve to death, because he could not hunt with pebbles for scales. Other than that, the fox is said (though only by Stonemover) to live a normal life.
Dinner arrived with a squirrel for Stonemover shortly after the first time he met his daughter, Sunny. She tried to shoo the fox away, but Stonemover told her he was Dinner, and that he animus-touched him to bring him food once in a while. Sunny remarked that it would be a bit creepy for Dinner if he knew what Stonemover named him. The NightWing noted that he hadn't thought of that before, since he'd never introduced him to anyone, and that he was sure Dinner otherwise still had an ordinary life as a fox. Dinner didn't remain long, and promptly left the cave once he gave Stonemover his meal.
When Moonwatcher went to go visit Stonemover, Stonemover complained that he was hungry. Although Dinner isn't mentioned in this part of the story, the fact that he was hungry means that Dinner hadn't arrived, perhaps because that was not one of the days Dinner was enchanted to bring him food.
- As stated and proved by Stonemover, living things can be animus touched, but one would have to put massive amounts of energy and concentration into them, although Darkstalker appears to be an exception.