Competing theories have viewed relationship formation as a gradual process or as an instant development, with little attention to differences in individual perceptions of the same relationship. In the present study, conceptual metaphors concerning relationship formation were identified and coded from interviews with each friend in 59 same-sex, white, college-age, US dyads (57% female). Friends were extreme and either very similar or different from one other with regard to extraversion–introversion. An actor–partner analysis found that friends paired with an extravert used more Force–Impact metaphors that conveyed an explosive ‘friends-at-first-sight’ experience, whereas friends paired with an introvert used more Journey–Organism metaphors that reflected a gradual transition into friendship. Regardless of their partner's personality, extraverts and female friends used more Joint–Proximity metaphors that emphasised the development of intimacy. Results are interpreted using the Social Relations Model and the PERSOC approach to show how personality can serve both as an environment (partner) and as a cognitive schema (actor) to distinctly shape impressions of how a friendship develops. Copyright © 2012 John Wiley & Sons, Ltd.