Jenibeth Blakely was the second child of Terrin and Alyst Blakely. Her siblings were Sabel Blakely and Ollus Blakely.
As a child, Jenibeth and her siblings were orphaned after their parents ejected themselves from their ship's airlock to prevent the Daleks from obtaining their knowledge of the Cradle of the Gods. The Eleventh Doctor discovered the three children hiding in the escape pod and they helped him discover how the intentions of the Dalek Foundation related to the Cradle and the Sunlight Worlds. While investigating Gethria, Jenibeth was taken prisoner by the Daleks and remained their captive for almost 90 years, during which she was converted into a Dalek puppet by Dalek nanogenes.
When the Doctor returned to Gethria, Jenibeth took him hostage and the Dalek time controller arrived with Sabel and Ollus as prisoners, blackmailing him to activate the Cradle and transform the Sunlight Worlds into Skaros. Fortunately, Jenibeth still had a child's mind since she was never educated and resisted the Dalek control. The time controller retreated after she killed the Dalek guards but not before shooting Jenibeth. As the Doctor set the Cradle to self-destruct, it fed off Jenibeth's mind and reverted the Blakelys back into children, also recreating their parents. They had no memory of the Doctor, who left without a word.
Jenibeth's favourite sweets were jelly blobs. (PROSE: The Dalek Generation)