When Esca adopts the wolf cub, it is very small, "warm and harshly furry...(with) a scrabble of paws and a thrusting muzzle". It has tiny, sharp teeth, is grey in color, and so young that it can barely walk, "stagger(ing) to uncertain paws...and...nuzzling (with the) thrust of all very young things". The wolf cub's mother has been killed while still in milk, and the rest of the litter, save for this one, has been killed as well. When Esca took the little cub, its sire tried to protect it and keep it from being taken, but Esca overwhelmed it in a fierce confrontation.
Esca feeds the wolf cub milk and scraps. He says that in his tribe, sometimes young whelps are taken to run with the dog-packs. If they are separated from their mothers early enough, "so that their first meat comes from their master's hand", Esca has found that they have a good chance of adjusting easily to domestic life (Chapter VI).
Marcus calls the wolfling by the simple name "Cub". Cub could be "a small fury...crouched over his food-bowl with laid-back ears and bared milk-teeth", but for the most part it is not long before Cub is "no fiercer than most hound puppies". Since the little wolf is "bigger and stronger for his age", however, he can "be very rough", and Marcus must keep a careful eye on him (Chapter VII).