Rosie was the target of Eddie Santini's affections, but when she rejected him he turned nasty and eventually forced her to transfer away from Sun Hill. Matthew Boyden also tried to ask her out, though she quickly brushed him off.
When Rosie returned to Sun Hill to investigate an explosion at a night club, she was revealed to be in a relationship with her (married) superior, DCI Pallister.
PC Rosie Fox first appeared in the episode Deep End. She immediately attracted unwanted attention from PC Eddie Santini, who had been assigned to an undercover investigation with her. Celebrating the successful completion of the job and egged on by colleagues, they kissed, but the night ended with Santini trying to rape Fox in the locker room. Santini later turned up at Rosie's house, repeatedly phoned her and harassed her at work, despite her asking him to leave her alone. Santini began spreading lies about her around the station, claiming that Rosie was obsessed with him and bullying and humiliating her at every opportunity. Team sadly believed Santini.
Paired together whilst hunting for a dangerous criminal (Bang Bang, You're Dead), Santini disobeyed orders and left Fox alone on the roof. She was subsequently attacked by the criminal, but Santini rushed back and managed to persuade their colleagues that he hadn't abandoned her. She filed a complaint against Santini for sexual harassment, though struggled to convince anyone besides Liz Rawton to believe her. Dave Quinnan tried to broker a peace between them (Team Spirit) but, tiring of Santini's behaviour, he revealed that Rosie had been telling the truth and that he had seen Eddie running back up to the roof. Though vindicated, Rosie nonetheless transferred away from Sun Hill.
Later on, promoted to Detective Sergeant, Rosie returned to Sun Hill to investigate the bombing of a nightclub owned by friend's of Santini's (Kiss Off). When Eddie's ex-girlfriend Jessica Orton was found dead in her home having fallen down some stairs, Rosie (rightly) suspected Santini himself of the crime and eventually linked him to it when he was found in possession of the keys to Orton's house. She arrested him for murder.
Rosie returned again for Santini's manslaughter trial, but was murdered in her hotel room before she could testify against him as part of the elimination of key witnesses by a major crime lord awaiting trial.
Rosie was one of the shortest cast members, as she only appeared in five episodes, three of which she was a regular character. She is beaten by Billy Rowan, who only appeared as a regular character in one episode.
Rosie was likely on a fast track scheme, as she was a PC in 1998, and DS by 1999. It is likely that she transferred to a DC post, and was promoted between her transfer and return to Sun Hill.