In our research nursery study of the emergence and vicissitudes of aggression, we had the opportunity to observe the unfolding of a particularly intense tormentor-victim relationship between two boys aged seventeen and nineteen months. Through the large body of developmental information we have accumulated about both of these toddlers, we have been able to explore the infantile roots of what we view as the erotization of aggression. We see the fusing of aggression with libido as playing a crucial role in both normal and pathological personality formation.