Olive was originally introduced back in the second Saturday Tales story with no context other than that they were at Plum's graduation ceremony. Olive then got a speaking role in the previous story with no additional context other then they were with Tawny, from the first story, and the other mouse character. This page explicitly introduces them as Olive and Plum's mother. Yes, Plum the cat has a mouse as a mother. I haven't explicitly decided the how's and the why's, or if I will even reveal any of that to the reader.
Looking at this page makes me realize I probably should go back in and add some light shading to the clothing. It wasn't super nessisary in the previous pages but I feel it is needed with the hat and robes. I'm just trying my best to do the least amount of work to convey my stories.