Help4Mood is a novel intervention to support the treatment of depressive disorder using an embodied communicative agent (Avatar) to engage the user with therapy tasks. We conducted 10 focus groups with patients and mental health professionals, in the UK, Spain and Romania, in order to explore issues around usability and contextual fit. Emergent themes related to the design and use of Avatars indicated the value of configurability for optimising personalisation and perceived trustworthiness; the importance of supplementing rather than replacing face-to-face interaction, and perceptions of the agent as therapeutic ally or supportive friend. The use of Avatars in psychotherapy is relatively new and its acceptability, value and risks are unknown. These results indicate that users wish to engage with Avatars that meet their personal preferences and fit appropriate role expectations. The perception of Avatar as colleague or friend raises conceptual and ethical issues which merit further research.