Most people remember first seeing Mortez break onto the scene as Hitgirl in Kickass. She packed a surprising amount of punch for such a young actress, but she actually has done far more subdued roles. Take for instance her role in Dishonored, as the heir to the throne, Lady Emily Kaldwin.
Mortez not only had to portray the character, but handle two completely separate voice overs due to the branching narrative. As a result, she played Emily as both a malevolent ruler to be, and as a peaceful idealist. Not an easy job for anyone, but Mortez brings something genuine to Emily that many young characters in video games lack. While Emily's looking all grown up in Dishonored 2, it's not confirmed if Mortez will continue voicing her or not.