Susan Felder (Kristy and the Secret of Susan)

Susan Felder is a character in the American children's novel Kristy and the Secret of Susan, which is the 32nd book in The Babysitters Club series.

Character creation
The character and surrounding story is partly based on author Ann M. Martin's experience as a therapist for autistic children over the summer during college. This is her second book featuring an autistic character, the first one being Inside Out.

Kristy and the Secret of Susan
Susan is the first child of Mr. and Mrs. Felder. Initially, she is very advanced in her development, and learns to walk and talk at a young age. Her parents look into progressive school, but at age 2.5 years old, Susan experiences an apparent regression. She attends a special school until she is 8 years old, after which she will transfer to another school with a strong music program (since she has extreme musical skills).

In the time between schools, Mrs. Felder fixes a babysitter from the Babysitters Club, so she have some time to herself. Kristy takes the job, and after a brief introduction, she is convinced that Susan should not be transferred to a new, faraway school, but should stay in the community and attend the local school special education class. Although she does not tell Susan's parents, her plan is to show everyone that Susan can do "normal" kid things. She takes her to play with some children who recently moved into the neighborhood from Australia, reasoning that both they and Susan need friends. One of the kids, James Hobart, does come to consider her to be his pal.

Multiple children come to visit Susan while Kristy is babysitting, asking her to display her savant skills such as telling the day of the week on which a date fell, or memorizing and replaying piano pieces upon first listen. Although Kristy is initially happy that people are coming over, it turns out that a local bully is charging his friends a dollar to come see Susan's talents.

In the end, Susan does move out to a faraway school. Her parents explain to Kristy that the local school would not be able to provide for Susan's learning needs, and Kristy accepts that Susan will not be attending the local school. Kristy wants to become a special education teacher in order to work with children like Susan.

Mrs. Felder is also recently pregnant with a girl who will be called Hope.

Baby-sitters' European Vacation
Susan makes a small appearance in Baby-sitters' European Vacation, where she is at a camp for disabled children.

Appearance
Susan is an 8-year-old girl.

Autism
Susan is stated to be autistic by her mother when she first calls the Babysitters Club. As an infant, she quickly developed and learned to walk and talk very early, but experienced a regression at 2.5 years old. She does not speak often and needs assistance in activities such as eating and bathing, which she could previously do on her own.

Susan has savant-like skills in the areas of music and memorization. She is a prolific piano player with perfect pitch, and can memorize and replay a piece after listening to it only once. She also sings, and can memorize the lyrics to a song after listening to it once, even if it's in another language. She plays piano often, usually classical, but has an enormous repertoire of songs committed to memory. She can also say on which day of the week a certain day fell (as long as it's not too long ago or too far into the future). Her mother thinks this is because she memorized her father's perpetual calendar.

She stims in a variety of ways, including flapping, hand-wringing, clicking her tongue, and waving her hands in front of her eyes. She does not make eye contact, instead looking above people's heads.

It is stated that her IQ is presumed to be under 50, although she is considered "untestable".