The main antagonist of Tales Of Graces, Lambda is a being of pure energy who possesses others. Sophie is his enemy, so he keeps low for a while while possessing Richard.
Lambda was abused by scientists for his limitless power supply, hoping to turn him into a battery to energize a different world. The experiments filled Lambda with intense hatred for others. Asbel convinces him to give humanity a chance, and he resides in Asbel's purple eye.