Manning is a lieutenant in the Imperial Guards of Rivilia, operating as a secret agent during escalating tensions with the rival nation Zafrin. His duties involve intelligence gathering and covert operations, including recruiting the young cadet Lean into the military by offering financial incentives to resolve Lean's familial debts after a funeral. Manning exhibits a pragmatic and opportunistic nature, openly expressing enthusiasm for profiting from conflict and destruction.

Characterized as charismatic yet morally ambiguous, Manning maintains unpredictable behavior. He operates with a blend of ruthlessness and occasional concern for allies. This is exemplified during a joint infiltration into Zafrin territory where he and Lean posed as lingerie salesmen to access an Armor excavation site. Manning prioritized intelligence gathering and theft of advanced weaponry, abandoning Lean amidst enemy forces when escape became untenable due to the activation of the colossal Armor unit Verifer. Despite this betrayal, indications exist that Manning retained some underlying investment in Lean's survival.

Manning's relationship with Lean functions as a dynamic pairing, positioning himself as the instigator of chaotic scenarios to Lean's reactive counterpart. Their interactions reveal Manning's tendency to employ metaphors and manipulative tactics, such as recounting a fable about foxes stealing chickens to rationalize his operational methods. No concrete background information regarding his origins, personal history, or development beyond documented events is available. His military strategies consistently focus on exploiting wartime opportunities for personal and national gain, aligning with Rivilia's objectives against Zafrin.