Fiona Frost/Relationships

Loid Forger
Twilight and Fiona, recognized as two of the most skilled agents within WISE, are frequently assigned missions individually. However, due to their exceptional abilities and effectiveness, there are instances where they are deployed together on the same missions to leverage their combined strengths. Twilight served as a mentor during her training as a spy, teaching her to bury her emotions and show no weaknesses. Likely because of the time she spent with him, Fiona's respect for Twilight turned to love and she now has a certain ambition to become his wife in place of Yor, whom she deems unsuitable for such an important role.

Fiona regards Twilight as an all-encompassing inspiration, be it during missions or in efforts to prevent internal conflicts. She consistently reiterates her unwavering commitment, affirming that she would go to any lengths for Twilight, even envisioning scenarios where she commits acts of violence on his behalf or sacrifices her own life for him.

Sylvia Sherwood
Sylvia is Nighfall's handler and one of the intelligence agents under her command. Unlike Twilight, Nightfall does not appear to experience significant pressure to undertake extra missions from Sylvia. However, she does participate in numerous assignments, frequently being deployed to accompany Twilight and provide support during his missions.

Despite their professional relationship, Sylvia has a suspicion that Nightfall wishes to make alterations to Operation Strix. Sylvia promptly warns her against planning anything reckless, but Nightfall clearly disregards these warnings.

WISE Agent
Both of them are field operatives entrusted with several missions. In the operation to apprehend their mole, Winston Wheeler, both Fiona and the WISE Agent were assigned alongside Twilight. While Twilight fulfilled his task of diverting the attention of the SSS, the two maintained close proximity to Winston, seizing any opportunity to apprehend him.

Yor Forger
Fiona believes Yor is lacking as Loid's wife and is jealous of the fact that a woman far less skilled than her in being a wife gets to be his wife and that Yor can manage to evoke some genuine positive emotion from Loid when in his company. After Yor utterly defeats her in a tennis match, Fiona declares her superior for now but vows never to give up on her love for Twilight, even going as far as traveling to the mountains to train her swing speed in preparation for her revenge match.

Anya Forger
Fiona believes Anya is not raised strictly enough and that under her (very painful) guidance, she can be made into a Stella Star procurement machine.

Franky Franklin
Fiona first meets Franky after Loid recommends him to her for help on a mission. When they meet, Fiona is initially unwilling to trust Franky, as she wants to resolve her mission as quickly as possible and is wholly unenthused when she has to play his girlfriend in disguise. However, after he attempts to protect her from an attack from a SSS agent and explains his neutral stance as an informant, Fiona begins to see Franky differently and decides to become a regular customer, to the latter's dismay, due to her "ugly" methods.

Yuri Briar
While Fiona had never met Yuri in person, she possesses certain knowledge about him. Fiona is aware that Yuri is Yor's brother and that he serves as a member of the SSS. Later, when Winston beat Loid, Fiona tried to convince herself that it was Yuri, showing that she was indifferent to the real Briar's condition.

Winston Wheeler
Fiona and her co-workers were tasked with catching the mole in their ranks, Winston Wheeler. Initially, she felt nothing but professional discontent towards him. However, it quickly turned into a personal vendetta when she discovered him in a fight with Twilight, which the latter lost. This circumstance and the fact that Winston was about to remove the mask from the unconscious Loid caused Fiona a furious rage, which she directed at Winston with the intention of stopping him. After learning Winston's ideology as a spy to never trust anyone, Fiona tells him he is weak because he has no attachments and that her attachment to Loid makes her strong. She proves this by beating Winston, although at the cost of her body.