A wolfbrother is a person who develops a relationship with wolves and some wolf-like characteristics. They can communicate telepathically with nearby wolves and will gradually develop golden eyes with very keen sight and hearing as well as an extraordinary sense of smell, able to discern other humans' and animals' emotions with considerable accuracy. They can also enter Tel'aran'rhiod or as they often call it the "wolf dream." Wolfbrothers are very adept in the dream, as powerful as Aes Sedai dreamers, and world and can communicate with the souls of wolves who have died and gone there (as can other wolves). This is shown in how Perrin Aybara is able to destroy balefire with the palm of his hand, dismissing it as "just a weave." If one does not hold oneself firmly in mind as a man, one may begin to truly think of oneself as a wolf and go mad, behaving like a wolf in the waking world.
To date all wolfbrothers have been male. Not much is known about the origins of the condition except that it is "older than the One Power", likely dating back to a much more primitive man. Stories of men running with wolves are older than the Age of Legends. Some wolves claim to have memories of their ancestors running and hunting together with men. Soon they will run with men again, to the Final Hunt. Although suspected by some Aes Sedai to have some involvement with the One Power, it is entirely unrelated to the ability to channel.