In this paper the author confronts the problem of how to make communication possible in the psychotherapy of child psychoses, in cases where the symbolic capacity is seriously compromised or never structured, and the self is extremely vulnerable, without a sense of temporality, and imprisoned in a “circular time” that seems incapable of articulations and resolutions. Through a brief clinical presentation, the idea is suggested of a “mediating object” – synthesis of the patient’s scanty and chaotic contribution and of the analyst’s reverie – on which to base a “transitional communication” that does not prematurely impose a separateness (implicit also in the interpretation) that the young psychotic patient cannot yet tolerate. A clinical vignette is then presented in which the role of “mediating object” is played by an invented fairytale that is progressively improved upon by the analyst and the patient together beginning with the very first “precursors” of the tale itself, and by an “omnipresent monster” who colonizes and imprisons every potential for psychic growth and symbolic competence in the child. The author shows how the fairytale constructed within the relationship begins to assume for the child the valence of a “shared dream”, there where he still had no access to a capacity for autonomous secondary elaboration. In conclusion, the author describes the narration of a fairytale as a “transitional” and complex relational event, and the various levels of functioning that are involved in a structurizing manner in the child’s relationship, not only with the tale itself as “mediating object” but also, and above all, with the story-teller as “mediating subject”.