A lone wolf is a wolf that lives by itself rather than with others as part of a pack. Most, if not all, lone wolves are ones that were banished from their packs such as a former pack leader or discarded pups (wolves prefer the safety of a pack; therefore, they almost never leave by choice). As such lone wolves are usually stronger, more aggressive and far more dangerous than the average wolf that is a member of a pack. They have difficulty hunting, as wolves's favorite prey are large ungulates, and it is nearly impossible for a wolf to bring one down by itself (hunting on their own can be done, as lone wolves are naturally stronger and some specialise in hunting moose on their own). Instead, they will hunt smaller animals and scavenge. Sometimes, a lone wolf will find another lone wolf of the opposite sex, and the two will start a new pack.
When used to describe a person, this term is applied to individuals who prefer solitude or who work alone. In literature, the term is used to establish a character as aloof and emotionally unable or unwilling to directly interact with other characters in the story. A stereotypical lone wolf will be dark or serious in personality; he is often taciturn, and will distinguish himself through his reserved nature.