Explicit emphasis is made in the books on the differences between Animagi and werewolves. Animagi have full control over their transformations and retain their minds, whereas werewolves' transformations are involuntary and include severe changes in personality. After the person has transformed into a werewolf he no longer remembers who he is; he would kill his best friend if he got anywhere near him. A werewolf only responds to the call of his own kind. The only way that a werewolf can retain his sanity, intelligence and memory while transformed is using the Wolfsbane Potion.