The appearance of virtual characters has been shown to impact the way people respond to the character. In helping contexts, building human-agent rapport is important for a successful supportive relationship. Positive first impressions will get the relationship off to a good start and are typically based on appearance and preferences or biases. We have conducted a study with 174 young adults (aged 18-30) to determine their preferences for the look of a character in a helping role with respect to the character's age, gender and ethnic appearance. After briefly meeting and ranking 12 animated characters, participants interacted with their top-ranked character. We measured the level of rapport established and general attitude to using virtual humans for support. About half of the participants said gender or ethnic appearance did not matter and preferred a peer-aged character that played the role of a friend. The other half preferred an older character who was female if they were female, or split if male. Significant differences based on participant gender, course studied, openness to experience personality trait and depression and anxiety levels were found for preferences but not rapport scores. Participants were mostly agreeable to using a virtual support person, though reluctant to recommend one to a friend. Our study identifies the importance of user profiling and tailoring of graphical models for certain personality types or psychological states.