Dr. Easter is a freelance investigator and cyberneticist operating as an 09 Case Officer under Mardock City law. He specializes in utilizing experimental technologies banned after the Commonwealth-Continent War, many of which he helped develop during his tenure at the Paradise research facility, where his work focused on advanced cybernetics and artificial intelligence constructs. He left Paradise due to shifting ethical priorities there.

He rescues Rune Balot after her near-fatal encounter with Shell Septinos, reconstructing her body using regenerative Lightite metal fibers under the emergency ordinance Mardock Scramble 09. This grants Balot technopathic abilities and enhanced physical capabilities. Easter partners her with Œufcoque Penteano, a shapeshifting artificial intelligence construct, to aid her adaptation and pursue a legal case against Shell.

Easter exhibits a distinctive eccentric personality, often dressing unconventionally while maintaining exceptional expertise in cybernetics and card games. He demonstrates strategic thinking during high-stakes casino operations, altering his appearance—dying his hair silver and wearing formal suits—to infiltrate establishments like Eggnog Blue. Despite his unconventional demeanor, he displays consistent compassion, particularly toward Balot, whom he gradually views as a surrogate daughter following estrangement from his biological child.

His professional dynamic with Œufcoque involves frequent banter and disagreements, reflecting a long-standing partnership built on mutual reliance. Easter's operational methods prioritize leveraging technology for humanitarian objectives, contrasting his earlier "For Science!" motivations during wartime research. He occasionally engages directly in field operations, such as wielding firearms against threats to Balot, though he typically avoids combat.