She was born to wealthy parents, but ran away from home when she grew tired of their strict lifestyle at age 11. Before leaving, though, she stole and ate a devil fruit her parents had acquired for a generous sum of money with the sole purpose of showing it off. Said fruit turned to be the Kisei Kisei no Mi, which granted its user the power of a parasitic being living within their own body. With the help of this parasite, which resides in her hair, she started making a name for herself from an early age, finally arriving at Thriller Bark through a commerce ship. There she met 6-year-old Ghost, after stealing food from a local restaurant he worked at and being caught by him. With Ghost growing tired of the monotony of his life, the two of them then made a deal: he would cook for her if she took him on adventures with her. It was during one of those adventures that Ghost found another devil fruit, but wouldn't find out what its power was until later.

During their teenage years, they met Draven, who was part of the Marines then. Despite their circumstances, the three of them grew close, only to be separated when Draven was sent somewhere else. Years later, they would meet again, and her and Ghost would join Draven's new-founded crew: the Phantom Pirates.

The Kisei Kisei no Mi

The Kisei Kisei no Mi is a paramecia type devil fruit which grants its user the power of a parasitic being living within their own body. Getting the hang of controlling a parasite at will is not easy, and it certainly wasn't for 11-year-old Calliope. Parasite was unpredicatble and uncontrollable at first, lashing out anytime it was hungry, making Calliope have to steal food to satiate it. Over time, the two of them began getting along, and Parasite became more tame. As long as she kept it well fed, it would answer to her needs and help her. Despite practically sharing the same brain, Parasite has an intelligence of its own, being able to like or dislike people and things. For instance, it likes good food, but dislikes annoying people (being this the main cause it developed a liking for human meat as well). Calliope also discovered it is rather vain, as it likes being brushed and clean and would lash out in annoyance whenever it got dirty or tangled. After learning it was just another living being, like her or anyone else, their relationship became easier.

Currently, Parasite is some kind of friend/pet for Calliope. She keeps it well fed, clean, brushed, smooth, and in return it behaves nicely and answers to her call. Parasite allows Calliope to use it as her main fighting tactic, though she can handle hand-to-hand combat quite well. Some of Parasite's abilities also include the toughening of hair (for shielding/weaponizing purposes), as well as shortening or enlongating it (more hair = more parasite).

The Will of D.

It was not until later in life that Calliope found out about the Will of D, and following this, the discovery that she also bore the initial D. in her name. She visits home one last time to learn the truth, but her father won't see her, as he knows she's become a pirate, and so she learns from her mother that his grandfather was Kuoni D. Rainer, captain of the Storm Pirates. However, her father, heavily displeased with her grandfather's story of piracy, cut him off and tried to bury anything related to him, to the point of completely changing his name. Upon unearthing this, she decides to find out where her grandfather is and meet him in person.

• Calliope and Parasite have separated stomachs; if Parasite goes hungry, it will start absorbing the food in Calliope's stomach.
• She likes praising Parasite after it does a good job, as she's discovered it makes it more compliant.
• Since she and Parasite share the same brain, whenever Parasite becomes unstable she does too, but to a lesser degree, and she knows how to handle it. Because of this, she can also know what Parasite thinks and speak for it when needed.
• She's the main source of advice for the crew. They all known they can come to her whenever they're troubled.
• She's protective of her fellow crew members, and will get terribly angry if any of them are hurt.