Discursive approaches to metaphor admit that divergent social contexts and discourse activities will affect metaphor use. Employing a descriptive text written by a participant with obsessive-compulsive disorder (OCD), this paper shows how, in a research context, metaphors serve a representational function and can also construct links between the researcher and the participant, produce a persuasive writing piece and build multiple identities. A discourse dynamics approach to metaphor can be joint with a systemic-functional approach to register to seize both the discursive functions of metaphors and their apparition as the text advances.