Grimson acts as chief of security for a powerful multinational corporation, presenting as a stern middle-aged man in formal business attire including a suit and glasses. His core function involves protecting corporate interests, particularly the Genocyber project and associated assets. He exhibits unwavering loyalty to the corporation's executives, driven entirely by a mandate to contain threats and eliminate liabilities—specifically the escaped subjects Diana and Elaine. He personally directs security operations to recapture or destroy them, confronting the pair directly in multiple engagements. Utilizing corporate security forces and advanced technology, Grimson pursues them with relentless, methodical focus to neutralize their threat to the corporation's secrets and stability.

This pursuit culminates in Grimson's death during a final confrontation. Attempting to eliminate the subjects personally, he is obliterated by a psionic blast unleashed when Elaine accesses the Genocyber entity's destructive power. No details exist regarding Grimson's background, personal history, or life prior to his corporate role. His character remains static throughout, defined exclusively by his security duties. He lacks any documented presence in spin-off media beyond the core OVA episodes.