One of the Synths that escaped the horrors of Lab 14 with Duncan, Aaron's ability is mind reading. Unfortunately, as all Synths weren't perfected before the accident, he is flawed. He is unable to zone into one voice, thus, he hears them all in his head. With Duncan's help in Colorado as he grew up, he learned to quiet the voices, but not eliminate them entirely.
Grim Judgment (A Grim Trilogy #2)
Grim Vengeance (A Grim Trilogy #3)