Since the concept of mourning has been taken as the object of study by psychoanalysis, there is a tendency to think as only as a capacity to experience and overcome the losses that occur during life. However, theoretical extensions allow us to also conceive of its important role in the development process from the earliest moments of an individual s life. Starting from the concept of fundamental mourning and its experience in early childhood, we promote a psychoanalytic reflection on the losses and the process of mourning, also addressing its interrelationship with the possibility of elaborating the mourning for losses in adult life. From Freud and his metaphor of the shadow in Mourning and Melancholy, we propose an understanding of how the lost object can either suffocate the ego with its shadow or enrich it with its light. In order to do so, we return to the concepts of introjection and incorporation, differentiating them, and we show that while the introjective processes are linked to the satisfactory elaboration of mourning, the incorporation would be more related to less healthy processes. Finally, the issue of acting out is discussed in the case of severe patients who may make an unconscious choice by sharing the same fate of the lost object in the face of the impossibility of drawing a loss. Such choice can be translated into engaging in compulsive behaviors, risky and or self-destructive situations, as well as direct and indirect forms of suicide. In this sense, fragments of clinical cases – the life and death stories – are presented to illustrate some of these situations.