Loid Forger operates under the codename "Twilight" as a master spy for Westalis's Eastern-Focused Intelligence Division (WISE). He discarded his true identity upon becoming an operative, a decision rooted in childhood trauma during the second East-West war. Orphaned after an Ostanian bombing destroyed his home in Luwen, Eastern Westalis, he joined the Westalian army at sixteen under a false name. His combat skill led to recruitment by military intelligence, where he adopted the philosophy "ignorance is weakness," dedicating himself to preventing children from suffering as he did. Trained harshly by handler Sylvia Sherwood for ten years, he became WISE's most effective agent, earning the title of Westalis's greatest spy. Pre-Strix missions involved infiltrating terrorist groups, manipulating targets romantically, mastering countless disguises, and mentoring agents like Fiona Frost (Nightfall).

For Operation Strix, a critical mission to surveil Ostanian politician Donovan Desmond, Twilight assumed the alias "Loid Forger," posing as a Berlint General Hospital psychiatrist. The mission required a credible family to enroll a child in Eden Academy, where Desmond's sons attend. He adopted Anya, an orphan with undisclosed telepathic abilities, from a dubious institution. Later, he married Yor Briar, a city hall clerk unaware she is the assassin "Thorn Princess." They adopted Bond, a dog from Ostanian experiments exhibiting precognition. Initially viewing Anya and Yor as mission assets, Loid developed genuine paternal and marital attachments, contradicting his belief that spies must avoid emotional connections. This manifested through protectiveness over Anya, willingness to sabotage missions for family safety, and sharing personal war trauma with Yor to affirm her place. Outwardly pragmatic, he internally intended to ensure their security post-operation.

Loid possesses exceptional espionage skills, combining intellectual brilliance with physical prowess. His cognitive abilities include eidetic memory, rapid data processing, and strategic analysis, enabling complex planning under pressure. He demonstrates mastery in hand-to-hand combat, marksmanship, infiltration, and vehicular operation. As a "Master of Disguise," he flawlessly emulates mannerisms, voices, and appearances, though heightened senses can detect him. His emotional intelligence allows precise profiling of targets, yet he consistently misinterprets the sincere motivations of Yor, Anya, and Fiona Frost. This blind spot stems from suppressing emotions during training and war to maintain operational effectiveness.

Personality-wise, Loid projects calculated professionalism during missions but faces increasing internal conflict between spy doctrine and family bonds. His core ethic forbids endangering civilians, especially children and animals. Initially strict and academically demanding with Anya, he adjusted his parenting to emphasize encouragement. Stress surfaces when missions deviate, like Anya's academic struggles or conflicts with Damian Desmond, sometimes triggering comical overreactions despite his composure. His character evolved from war-fueled hatred to a commitment against violence, realizing blind obedience and ignorance perpetuate conflict. This ethos underpins his dedication to Operation Strix's peacekeeping objectives, even as his personal investment in the Forger family transcends its original purpose as a facade.