Mentors' initial perceptions of the mentoring role in formal youth mentoring bonds; and the subsequent characteristics of autonomy support or autonomy control in mentoring interactions developed by mentors after 5 months of mentoring experience are discussed in this paper. The data is drawn from a longitudinal phenomenological study conducted in the Czech mentoring scheme between 2010 and 2017. In-depth semi-structured interviews were collected with 10 mentoring matches over 1 year of mentoring involvement. The results of Interpretive phenomenological analysis showed differences in mentors' initial perceptions of the role, and related autonomy-supportive or autonomy-controlling characteristics in mentors' approach. The benefits and risks of resulting autonomy support or control in mentoring interactions are discussed. The results argue for the theoretical conceptualisation of a child-centred perspective in youth mentoring that aims at mentees' support of autonomy, active agency and empowement, thus arguing for further in-depth exploration of natural mentoring principles in child-centred perspective, supporting approaches such as youth-initiated mentoring, and broadening the discussion on good evidence-based mentoring practice in the EU context.