Index is a white rat once owned by Labrats Inc, a company specialising, funnily enough, in the breeding of white laboratory rats. She grew up rather quickly as rats do, and at only a few months old managed to escape and set out to discover her purpose in life.
An opportunity arose when she ran into Tam-Tam, a Roomba who wanted to be a musician so badly he gained sentience. He asked Index to help him become a musician, and she obliged, becoming a self-taught engineer in the process and constructing a new musical body for him over the course of two years in which time they became good friends. Now, with her third and likely last birthday looming on the horizon, she and Tam-Tam strike out into the wasteland in the hopes of discovering a way to live forever. After all, who will take care of Tam-Tam if she passes away?
Index is played by Rowan, who joined the Penance RPG family in August 2017 playing Andreadina in the Original Series.