The Savage interaction is only available to Werewolves. Once initiated, the werewolf attacks the non-werewolf, initiating a fight. During the fight, lycanthrophy is transferred to the victim. If not close friends or lovers, the victim will become furious at the attacker. If they are close friends or lovers, the attacker will gain relationship points, and the victim will lose relationship points. If a werewolf from another family is on your lot, you can influence them to fight with another Sim, like any other sim can be influenced this way. However, because you have influenced a werewolf, it will count as a savage, and thus turning the sim you wanted the werewolf to fight with into a werewolf themself.