Josslyn John Jacks, daughter of Jax and Carly, entered the world prematurely while her mother was held captive by Claudia Zacchara. Claudia intended to kidnap Josslyn but her plans were thwarted by Josslyn’s half-brother Michael. He killed Claudia and recused his baby sister and his mother. Not long after Josslyn’s birth, the relationship between her parents deteriorated and Josslyn became gravely ill. She was diagnosed with cancer in both kidneys and required a kidney transplant. Josslyn received new kidneys from Jacob Spencer, the son of Jason Morgan and Elizabeth Webber, after his unexpected death.
Josslyn survived the transplant but the marriage between her parents did not. After a brutal custody battle, her mother was awarded sole custody. Her father disagreed with the court’s decision and kidnapped her briefly but she was returned and Jax left town. Josslyn was briefly kidnapped again, this time by Ewen Keenan, under the orders of her uncle Jerry. Josslyn was injected with an unknown substance which caused her to experience an extremely high fever. The substance was later revealed to be an inoculation to a deadly toxin which Jerry had released into the Port Charles water supply.
As time passed, Carly allowed Josslyn to visit her father in Australia but her primary residence remained her mother’s home. Josslyn was not pleased when Carly’s boyfriend Franco moved in. She made her disproval of Franco known through her words and actions. Meanwhile, Josslyn attended a summer day camp with other children, including Spencer Cassadine. They became friends and she hid Spencer in her bedroom when he ran away from home.