This paper critically reexamines recent arguments about spirit possession as an embodied collective memory indicating the following points: (1) It does not provide a full accounting of the relation of the embodied past and a constitution of a particular memory or history about that past. (2) It puts spirit possession in the social context arbitrarily selected by anthropologist, and reduces the behavior of spirit possession to a static social role (personage). That eliminates a multiplicity of spirit-possession behaviors. (3) It does not fully investigate the uncanny and emergent aspect of spirit possession that deviates from the social code of self-fashioning in each case. From those reflections, this article examines the uncertainty of spirit possession in the local context of the Comoros. As a technique of metamorphosis, spirit possession is not a chaotic, uncontrollable action of trance or madness, but a well-ordered behavior that attributes other subjects to the body in the non-ordinary social code. Many anthropologists find that masters play ordered roles in the stage of the theater of spirit possession, despite the appearance of disorder, and a reasonable explanation can be made of 'symbolic expression' or 'social function.' We may be able to regard spirit possession as a way to domesticate the contingency of the body and events of life and socialize the human being. But spirit possession begins from the anarchic convulsion of the body, and that repeats during each incidence of possession. As symbolized by such convulsions, spirit possession concerns the contingency of the body or the unpredictability of life events. As a matter of fact, during the real event of spirit possession, we can obviously find much uncertain action or ambiguity of discourse that seems to reject any explanation. The spirit continues to be the radical 'other' that human beings cannot dominate by discourse. In the practice of spirit-possession practice, the essential contingency or uncertainty of the body or events may not be integrated into the consistent narrative as a collective memory, and suspended to a long-term redundant negotiation with the spirit as an uncertain 'other.' This article draws focus to such an uncanny aspect of spirit possession. Specifically, an analysis is made of the process of self-fashioning in the case of a long-term relation between a woman and a spirit over three generations in the Comoros, followed by a discussion of how spirit possession can still be beyond our understanding.