Derek's fox (Sterek)
Peter Hale finds young fox in the woods when he was on a run a few years back, and just couldn't leave the baby fox by himself, he takes him back to the loft he is currently sharing with his nephew, Derek, and decides he would keep him as a pet.
The next day he couldn't find the fox, but a young boy in its place with deep orange, bushy ears and even bushier and brighter tail. Peter decided to raise the boy as his own, considering the boy only knew his name and nothing else... Stiles.
As the years go by, Stiles becomes more and more attached to Peter, and more importantly to Derek. Derek also starts feeling closer to the fox shifter, showing more affection towards the boy, but also constantly worrying about him.