Little is known about Karla's past, except she grew up with her sister Stella.
After the apocalypse, she and Karla met up with Sam and a university professor (it is not known if they knew each other before this). While in Vancouver, they met Ben Parker and Randall Wayne. They went to Seattle together, losing the university professor in the process. A few days later, Karla left the barn alone and got bit. She was put down by Randall.