Louis is a werewolf who can shift into his wolf form at will. He is usually quite docile in his wolf form, but every full moon he becomes a monster with a singular desire to kill. He is unable to take his human form during the full moon. He usually prepares for this event by running deep into the forest to avoid hurting anybody. During a lunar eclipse or a new moon, he becomes very weak and cannot take his wolf form at all. He is highly allergic to silver, and he can be incapacitated for at least a week if any amount of silver enters his bloodstream. Silver alone can not kill him, however. He can only die if his brain or heart is completely destroyed.

In his human form, Louis has messy brown hair, blue eyes, and usually a beard. He has unusually sharp canines. He typically wears loose clothing and no shoes to make shifting easier, but he can blend in with normal humans if he has to. He tends to feel anxious as a human, but outwardly he acts cool and calm. In his wolf form, Louis is a shaggy, white-furred grey wolf with big paws and yellow-green eyes. His thoughts are a bit more simplistic as a wolf, and he is more easygoing. He has a friendly, "puppy-dog" nature except during the full moon. He has a long, thick scar on his right hind leg in both human and wolf form and he is reluctant to talk about it.

He owns a house in the village but he rarely occupies it, preferring to roam the forest as a wolf. He enjoys hunting alone and with friends, and he is quick to share a kill. When he does stay in his house, he likes to use his computer and hang out with his friends. He also sets out food and treats for the local wildlife, so his house is often occupied by all sorts of creatures.