Chapter 1: Humans

In Age of Extinction, Optimus Prime is found by Cade Yeager, along with his daughter and her boyfriend. But in Trust Before Truth, Shane's sister is able to track Shane down after he disappears.
Shane's father left them right after Alice was born, not because he was a bad person, but because he wanted to protect them. Alice inherited her father's endothermic and exothermic powers, so she is able to manipulate heat, but Shane did not.
When Alice joined the Autobot group to protect her older brother, she becomes a valuable friend to Optimus Prime and a dangerous and powerful enemy to the government and Decepticon forces.