Mary is a Go-With-The-Flow, Shrew, Shy kind of girl that obeys commands at her own risk. Mary is usually always frightened even by her own shadow, And has a big fear of her Sister-In-Law, Veronica Snaptrap.
Mary bears a strong resemblence to her father, Except she wears a grey labcoat with a forest green skirt. She also has the same ratty hair as her father, And the same glasses. She also wears light pink lipstick with long, spikey eyelashes that are similar to Larry's eyebrows.
Though Tiffany and Mary seem to have a molecue-sized relationship between each other, Tiffany appeared to show a caring side for Mary in the fan episode "Pup Mommy" Where Mary was turned into a baby along with her crew.
Mary and Helen never seem to have a good relationship, And they dislike each other for everything, Their looks, Their clothing, etc. Surprisingly, Mary an Helen never seem to get in good contact with each other, And they never seem to get along.
They can never seem to get along well ether. Veronica usually ends up dunking Mary into the Shark Tank, Because of Mary's whining and antics. Is it revealed that Mary often dreams of Veronica exploding and putting a Cobra in her dress; And that they are Step-Siblings due to Mary marrying Veronica's older brother (Who is unknown).