Arthur Cummings Jr., aged seventeen, shares the distinction of being the oldest surviving member of the Cosmic Culture Club alongside David Rutherford, following the Gradosian assault on the United Nations Mars base. He exhibits pronounced emotional instability, frequently revealing cowardice and a fragile will through unfocused ramblings and volatile outbursts. Despite these traits, he sustains amicable bonds within the group and functions as Roanne Demitrich's chief confidant, anchored by their preexisting friendship.

His psychological vulnerability renders him easily manipulated, especially by Simone Reflann, toward whom he nurses an intense, unreturned romantic attachment. Simone leverages his "eager to please" disposition to direct his decisions and behavior during their shared crisis.