Fiona Frost

Fiona Frost, codenamed Nightfall, is a skilled spy working for the Westalian intelligence agency WISE in the Spy x Family anime. She serves as a supporting character introduced in Season 1 (around Episode 20-21) and becomes more prominent in Season 2.

In the anime, Fiona is depicted as a tall, attractive woman with pale skin, a slender build, and distinctive white/silver bobbed hair (with a long fringe often covering part of her face). She typically maintains a completely emotionless, stoic expression and speaks in a flat, composed manner, giving her a cold and intimidating presence.

She was personally trained by Twilight (Loid Forger) earlier in her career, and she took his advice to heart—suppressing all visible emotions to become the perfect spy, vowing to remain "stone-faced" forever. This makes her appear ruthless, ambitious, and perfectionistic to those around her.

Beneath this icy exterior, however, Fiona harbors intense romantic feelings for Loid/Twilight (her inner thoughts are often giddy and lovestruck, which Anya picks up via telepathy for comedic effect). She views herself as a far superior potential partner for him compared to Yor and occasionally schemes (or fantasizes) about replacing her in Operation Strix, though her superiors keep her in check to avoid jeopardizing the mission.

She works undercover as a clerk at Berlint General Hospital to support Loid's cover and occasionally assists on joint operations, showcasing her competence as a spy while adding tension and humor through her one-sided rivalry and hidden devotion.