2 ideas
Petra's confinement to the documentation office reflects the sexism of her institution, which kept her away from active investigative work. She reaches a major case only because a staffing gap opens, not because the force recognized her competence. She must then prove herself on the job.
Petra is a sardonic, divorced, independent modernizer, and Garzón is a courteous, old-fashioned widower with traditional views of women. The friction between them works as a two-way check rather than a conflict to be won. Each partner's blind spots are exposed by the other's instincts, so respect grows through repeated small concessions rather than through ideological conversion.