He was first seen near Los Angeles Basin, California, where he was preparing to shoot Max. After tracking the Flock, he thought about the gun on his arm and how the CSM was supposedly wasting everyone's time with their air shows. He then angled the gun to the left and fired a shot.
Angel managed to push Max away from the path of the bullet, though Total took the hit instead, though not directly as he lives on. This caused the Flock to notice Devin and plan to take him out. They never got to do so, however, as he self-destructed as they were dive-bombing the building he was in.
Devin was said to have had an IQ of at least 220, enabling him to make extraordinarily quick calculations. He also had a Glock 18 grafted to his wrist where his hand should be; it was done in such a way that "the weapon was a part of him physically", responding to his thoughts almost instantly. In addition, he also had incredible eyesight—though not at good as the Flock's raptor vision, he believed it to be good enough.
After he self-destructed, all that was left of him was part of one arm.
He is also featured in the manga Maximum Ride 8, trying to shoot Max, but failing, before that he said "How hard is it to kill one bird kid. Only stupid pathetic losers would fail.".