Like Raven, we first meet Mila and Maddie in Through Shade and Shadow, though they are largely relegated to the background. When we first meet them, Alaric and his friends, following a vision, help them escape from the 8th Battalion along with Sahara.
Mila is nineteen. Maddie has just turned sixteen. Through that first encounter we learn that Shifters go through a change with puberty, and before the start of puberty they can not shift into animal form. During this period, the Shifter is not fully in control of their shifting, and strong emotion or pain can cause unexpected shifts.
It is this problematic effect that leads to the girls getting caught by the 8th Battalion. We don’t know a lot about what they went through while they were prisoners, but we can be fairly certain that pain was involved.
In In Gathering Shade, the girls get a chance to come out of the background a little bit. Unlike Sahara, who’s cat is a lioness, Mila and Maddie are black jaguars. While living in the camp where Alaric brought them after their rescue, the girls help out by hunting large game to feed the growing population of their hideaway.
Mila is a leader, and she struggles under the rules of the camp and the impression that Sahara speaks for the sisters simply because she’s older. Maddie is the more sensitive of the two, seeing herself as a freak who just wants to be normal. This feeling is not surprising, considering that she is both a Shifter and a teenage girl.
Both girls were fairly sheltered growing up, and their understanding of the world is somewhat skewed by that, but they will have to find their feet fast if they are going to survive the war that is coming.