The author addresses the siblings theme not only by considering it part of the bonds of a concrete and real family but by relating it to more phantasmal analogies in order to give voice to the world of internal representations. This paper is inspired by some fundamental considerations formulated by René Kaes in the book “The fraternal complex” (Le complexe fraternal, 2008): n the fraternal complex two different levels can be identified: 1) an archaic level characterized by a pre-Oedipal climate in which confusion and undifferentiatedness prevail and where the brother or sister assumes the uncanny dimension of a foreign object, a non-recognized, encrypted and encysted double or lookalike. 2) a level of Oedipal nature in which the otherness, the difference and the recognition of the other can be structured; this level makes it possible to open up towards a dimension of separation and identification. These two different levels will be illustrated trough some clinical situations.