Born to Dale and Stacey Yorkes, Gert long resented her parents' choice of name for her, believing it to be too old-fashioned. It later turned out that her assumption was correct, as her parents were time travelers and members of the Pride. After witnessing a human sacrifice committed by her parents, Gert and the other Pride members' children decided to run away. In the process, Gert learned that her parents had genetically engineered a Deinonychus named Old Lace that possessed a telepathic link with her, allowing Gert to command the dinosaur. She remained a member of the Runaways until her death at the hands of a new version of the Pride. Her death particularly impacted Chase Stein, who had developed romantic feelings for her.
A few years later, Chase used the time machine once owned by Gert's parents to travel back to the date of her death, returning her to the present and saving her life with help from Nico Minoru. Her resurrection ultimately led to the reformation of the Runaways. Due to the age disparity now existing between her and Chase, they mutually decided to break off their romantic relationship, with Gert ultimately falling for fellow Runaway Victor Mancha.
Gertrude Yorkes is the daughter of Dale and Stacey Yorkes and the adoptive sister of Molly Hernandez. Upon reuniting with her childhood friends, they discovered that their parents used PRIDE to cover up ceremonial sacrifices of the Church of Gibborim in order to restore Jonah, their benefactor. She and Molly also found out that Dale and Stacey genetically engineered a Deinonychus, with whom Gert shared a telepathic link, being able to control the dinosaur. She teamed up with her friends and formed the Runaways, to stop PRIDE. Having been framed for Destiny's murder, and with no other choice, they are forced to run.