The Doctor becomes a celebrity among an alien people.
Voyager helps the Qomar, a technologically advanced but arrogant people who look down on everyone, including the holographic Doctor. Then they hear him sing and are captivated, because they have never known music. They invite Voyager to their homeworld, broadcast the Doctor's concerts across it, and turn him into a star with legions of fans.
The fame goes to the Doctor's head, and he resigns from Voyager to stay with the Qomar, hurting Seven of Nine in particular. But the Qomar soon build a new singing hologram with a vocal range no human could match, and the Doctor's career ends. Realising they valued his voice and not him, he asks to return, and Janeway takes him back. The sixth-season episode is a comedy about celebrity and art, and it ends with Seven giving the Doctor a fan letter she has written herself, praising both his talent and his character.