One plot idea could be that the male reader is a new recruit in the city's guard. He catches Emily's eye during a patrol when he shows extraordinary courage in the face of danger. Emily then begins to secretly train him in her stealth and combat techniques, and as they spend more time together, a romantic relationship blossoms. This could involve them going on secret missions together to protect the city from threats.
A different plot idea might be that the male reader is an inventor. He creates a unique device that Emily believes can help her in her fight against the corrupt forces in the city. She seeks him out, and they start working together. As they tinker with the device, they also start to develop feelings for each other. This could lead to a story where they use the device to take on the city's villains and also deal with their new - found love.