Jonathan Green is a Reclaimer and a pilot of the Antibody mecha known as Grand Cher, serving the faction known as Orphan. He is a young man of 24 years with blonde hair and blue eyes. His background is defined by a painful and lonely childhood. His mother, Captain Anoa McCormick, was a workaholic who was largely absent from his life, leading Jonathan to feel abandoned and to develop a deep-seated resentment towards her, though this feeling is complex and intertwined with a lingering desire for her affection. This emotional neglect is dramatically illustrated by his anguish over receiving a gun as a gift, which he interpreted as an unacceptable substitute for the simple Christmas presents he had longed for as a child.

As a result of this early isolation, Jonathan has cultivated a bitter and aggressive personality. He craves recognition and power, positioning himself as a rival to Yu Asami, whom he resents for the family love and favoritism that he himself was denied. This bitter envy fuels his primary motivation to prove himself as the strongest Antibody pilot by defeating Yu in combat. His ambition does not stop there, as he also frequently competes with his superior, Quincy Issa, for control over the Reclaimers, and ultimately desires to rule Orphan itself. Despite his cruel and taunting demeanor, which includes lying about having affairs with Yu’s relatives to provoke him, Jonathan shows an unexpected and gentler side in his interactions with children. His fear of living and fighting independently suggests that his constant drive to dominate others is a shield covering a deep-seated insecurity.

Within the story of Orphan, Jonathan is an eager and powerful frontline fighter. His skills as a pilot are top-class, yet he consistently finds himself outmatched by his rival Yu, which only exacerbates his frustration. His desire for strength and a sense of belonging leads him into the orbit of the mysterious Baron Maximilian, to whom he transfers his undying loyalty, filling the emotional void left by his mother. This relationship is the most significant in his character arc, as the Baron provides him with a special Antibody called the Baronz, which is powerful but damages the pilot's mind. Jonathan remains unaware for a long time that Baron Maximilian is, in truth, his own mother, Anoa McCormick, who took on that persona to watch over and care for him from the shadows. Her tragic defeat and death at his hands ultimately lead to a moment of reconciliation, allowing him to finally come to terms with his estranged mother.

Jonathan pilots a Grand Cher with a yellowish-tan or黄土色 (ochre) color scheme. In battle, he notably lost his mech's left arm to Yu's Brain, after which his unit was fitted with a distinctive hook-like prosthetic in place of the missing limb.