Throughout the Voyager series, the doctor struggles to define his identity and to understand his place within the fabric of social structure. Despite superior knowledge of medicine and skill that rivals any human doctor, he is not considered desirable as a physician or as a friend because of his status as a hologram. The dilemma typifies problems faced by people of differing racial backgrounds. It also often demonstrates problems faced by people with disabilities. The doctor has particular strengths but also lacks knowledge of social skills and nuances that are necessary for success. He develops these things as he interacts with people more often; but people must risk interaction with him before this can happen. He makes friends over time but continues to feel an emptiness inside, a longing for a greater ability to fit in. His professional identity does not give him a sense of completeness; and he reaches for more and more ways to build his sense of self. Some of the things he enjoys end up creating uncomfortable situations for him.
In the episode, "Virtuoso," Voyager's doctor encounters a painful familiar scenario: people who need his services think he is not really capable of performing the task. The difference, in this case, is that his patients are members of an advanced species who not only dislike him because he is a hologram but also dislike humans because they are an inferior species. When his patients speak in front of him using overexaggerated speech, he returns the favor and returns to his work, humming cheerfully. His humming, which often irritates his shipmates, captivates the aliens, who have never heard music. The doctor rises quickly to become a celebrity on their planet. Soon he garners invitations to perform for large audiences, and one of the aliens composes a complicated piece and asks him to perform it for her. Flattered by her attentions, the doctor submits his resignation to Captain Janeway and begins making plans to stay on the planet to explore his dream of becoming an opera singer. His dream is shattered when he finds himself unable to perform the alien's piece. He learns that attention is not always based in love.
The fate of his relationship with his musical fans is often the fate of people whose relationships are built on admiration, especially when the admired person has worked hard to develop a particular skill set in order to make the relationship possible: the relationship is possible only as long as the skill is good enough for the demand. The result is disastrous when the demand exceeds the skill level.
The struggle for depth in relationships is common. As Seven reads fan mail to the doctor, I think that perhaps depth is not so far away as it sometimes seems...