A pair of unnamed (to Francis's knowledge) coal-black sisters of Oriental breed with Mediterranean-colored eyes was encountered by the detective during his first meeting with Adrian.
They flirted with him, alongside Fabulous, and witnessed the first clash of investigative skills of Francis and Adrian.
They were actually not fully mature she-cats, showing a slender "teenager" physique.
Later, Francis meets them in distress in the snow because they got lost and explained of living in the neighborhood in only one month. One of them appeared older than the sister, but it is possible they shared the same age and one of them was simply more self-confident.
While accompanying them home, Francis learned decisive clues to solve the case, because the black females made important revelations regarding Fabulous (who they befriended and were actually searching for in the snowy night).
While escorting them back home (and before making inquiries about Fabulous), Francis envisioned how he would have put the two she-cats on his top list of "priorities" for the next summer, implying a desire to search and mate with them.