From Cassius Comics

Real Name: Nathaniel Essex

Arguably the most skilled geneticist ever to exist, Nathaniel Essex is a frequent servent of Apocalypse. Having long since determined that the spawn of the Summers and Grey bloodlines would produce one of the most powerful mutants imaginable, Essex subtly influenced and monitored the two families until Scott "Cyclops" Summers and Jean "Phoenix" Grey produced Nathaniel Dayspring, the child who would become Cable. Although Essex has attempted to gain control of both Dayspring and his alternate-dimensional counterpart X-Man (Nate Grey), neither venture has proved successful.

Essex possesses complete control of his body's atomic structure, and can heal from nearly any injury. He can also project bursts of energy from his hands.

Essex has teased Cyclops in the past with supposed information about a third Summers brother (the second being Alex "Havok" Summers), but he has yet to reveal the man's name, or anything concrete about him.