Rachel Argosy was a late bloomer in terms of her mutation. She contracted spinal meningitis as a child and the illness delayed her mutation until early adulthood. Foreshadowing a mutant gift in music, she became an accomplished violin and flute player. This led to her career as a high school music teacher in Two Forks, Maine.
Soon after her tenure, her skin turned blue and she realized her music had a much more profound affect than she ever thought possible. Her students enjoyed the addition of her powers, presumably because they were able to understand music on a grander scale. Unfortunately, when the students’ parents caught wind, they complained to the administration and the school board let her go.
She then attempted to use her powers to make Harry Sharp, the leader of the school board, change his mind. In doing so, the mutant mistakenly sent him into cardiac arrest, killing him. Quicksilver and Madrox of X-Factor were sent to apprehend her.
Despite her best attempts at proving her innocence, Rhapsody was ultimately found guilty of causing Sharp's death, resulting in a prison sentence. This is likely where she remains to this day.
She is one of the 2% of mutants to retain their powers post-Decimation.
Rachel is able to use the music she plays to warp reality with a variety of effects such as producing hallucinations, mind control, possession, emotion manipulation, and even flight. Rhapsody’s physical mutation is her skin, which has an azureous hue. Aside from these, she is also a talented violinist and flautist. These two instruments are most often utilized in harnessing her powers.