When Lucius asked, why some werewolves were violent and bloodthirsty. Fenrir withheld a growl and explained to him that only rogue werewolves or werewolves with no real pack were dangerous, violent and mad. Lucius had to admit that Remus Lupin was an example, who didn’t have any real pack. The man saw the Potters and Sirius as his pack. When Narcissa asked about Remus Lupin, Fenrir immediately told them that the man was an example of a werewolf that didn’t have any real pack, since the Potters and Sirius were humans. In a pack, no matter what size, there must be at least one werewolf or another magical creature, so that the wolf could feel comfortable with another magical being.