Characteristics
Susanna Test (voiced by Ashleigh Ball) is a 13-year old super genius who was the older sister of Johnny and the daughter of Hugh and Lila. Susan has been shown to be less empathetic and sympathetic than her sister. Like her best friend, Susan herbs a deep love and obsession for Gil.Bling Bling Boy has a huge crush on Susan but whenever he tries to get her to fall in love with him it always fails. Like her sister, she attends school at the Mega Institution of Geniuses. Susan is prone to believing in the more scientific and less science-fictional, which although gives scorn to her twin, Mary often proves to be right in the end. Susan seems to be less level-headed than her twin Mary, and Susan tends to be less conservative, as she speaks her mind much more than Mary. She is the younger of the two.
Appearance
She has completely straight red hair and has navy blue eyes and wears square glasses. She wears a shirt with a star on it and a yellow star-shaped barette in her hair. She one day hopes to meet a star. She is always seen wearing a light gray lab coat, black skirt and pumps with a light blue shirt with a navy blue star in it, and black Mary Jane shoes. She sometimes wears a greenish blue one piece swimming suit and her disco outfit was a greenish blue tank top with a black skirt, a greenish blue cap, bright greenish blue socks, and dark pink shoes. and black shoes. She first appeared in Johnny to the Center of the Earth.