Maritza is Kathy's grandmother and the mother of Kathy's father Edward. Kathy lives with her after her parents discovered her pregnancy.
Maritza is very kind to Kathy and goes out of her way to make her happy. She constantly tells Kathy that her home is also Kathy's home. She is also more trusting of Ethan than Kathy's parents are.
She doesn't seem to have much of a relationship with her son, but knows him pretty well, warning Ethan of his hard personality.
- In earlier episodes, Maritza never discloses that she is Kathy's paternal or maternal grandmother, but in a later episode, it's revealed that Maritza is the mother of Kathy's father Edward when he and Ethan are talking about her absence, leaving him and Kathy alone.