Who is Madelaine Tock from Life Expectancy and what is their importance?

Jimmy Tock's mother Madelaine earns a small income by painting portraits of pets on commission. She paints dogs, cats, and less frequently rabbits, parakeets and even a milk snake once. She has a good sense of humor, and a tolerance for caffeine that is nothing short of remarkable. Like the rest of the Tock family, she also has an efficient metabolism, enabling her to consume large amounts of food in a sitting without becoming overweight.