She is portrayed by child actress Jordyn Orr.
Sue announces that she wants to have a baby in The Spanish Teacher, the twelth episode of Season Three. She asks the Glee boys to donate to the local sperm bank in order for her to select a suitable father. In On My Way, Sue informs Quinn that she is pregnant and that the baby's father is a celebrity.
In Big Brother, Sue discovers that the baby is a girl and has some abnormalities. Becky comes to Sue and she tells Sue that she heard about the baby's condition. She tells Sue to be patient with her.
Sue announces that she is pregnant, but refuses to reveal who the father/donor is.
Sue goes to a check-up, where it is revealed that Robin will be born with Downs syndrome.
At some point between Season Three and Four, Robin is born.
Robin doesn't make an appearance, but when Sue shows evidence that Brittany is failing her tests and is a bad example for the cheerios, Sue holds up Brittany's algebra sheet, to which Brittany got an F- for writing "see other side" to all the answers. On "the other side" is a picture of "Happyville" Brittany drew. She says that Sue can see Brittany and Santana, Kurt, and Rachel and then Sue can see a drawing that Brittany made of Sue and Robin. Sue admits that she let her pregnancy hormones control her, letting Brittany slide academically.
Robin doesn't make an appearance but Sue puts on Will's résumé that Will took Robin out of Sue with his bare hands even though it was a lie, so that he could easily get out of McKinley on a show choir committee trip. She comments that for the first time, she wants him out of McKinley in a good way.
Robin does not make an appearance, but when Finn casts Wade/Unique as Rizzo in the school production of Grease, Sue won't allow it. She puts up a fight with Figgins, Will, and Finn. In Figgins office, Sue continues to fight. But when Finn has enough, he yells at Sue and says he thought she was a better underdog, helping New Directions win Nationals the previous year and having a "retarded baby" referring to Robin. This throws Sue in an angry fit and makes Finn her enemy. This has obviously been a wrong choice of words. Later when Kitty finds out that she is cast as Patty Simcox, she goes off in a rage and Sue says to her that Robin needs to be fed.
The narrator is referencing the "retarded" word incident, when the narrator says those Robin appears in a flashback for one second.
Robin makes an appearance when Sue sits next to Emma in the audience. She carries Robin, explaining that Robin is a very fussy baby and will be wailing throughout the entire performance, when New Directions takes the stage. Emma looks on with a content expression.
Coach Roz Washington refers to her by calling Becky an "Adult Baby Robin".
In the episode of Fondue For Two with Sue, Will and Brittany, it is revealed that Robin's father is Michael Bolton, despite Sue's attempt of initially denying it. In Robin's birth certificate, it is stated that she was born in "Ol' Milton Beach," an anagram of Michael Bolton and Brittany adds that in Michael Bolton's latest album, the first track is called "So Proud to be Your Father, Robin Sylvester".
Robin is mentioned by Sue when she makes the morning announcements late, by stating she was openly breast feeding her daughter at Starbucks.
She is mentioned by Sue when Sue talks to Will about her copulate with Michael Bolton.
She is mentioned by Sue when Sue talks with Mario.
Robin was mentioned when Roz mistook Becky for Robin and Sue had to explain that Becky, Jean and Robin all had Down syndrome.
Robin was mentioned when Geraldo Rivera, a Fox News reporter states that Sue may just be compulsive liar, referring to how the father of her child was, Michael Bolton. She states that it's true but he shows her a video of Bolton stating that he didn’t know who she was, until she made those claims.
- She is named after Robin Gibb, Sue's "favorite dead Bee Gee". (The New Rachel)
- Although a normal pregnancy lasts for about nine months, Robin was born after only seven months of pregnancy. This means that Robin was born a premature baby.
- In real life, Robin is named after Robin Trocki, the actress who portrayed Jean Sylvester. The actress who plays Robin, Jordyn Orr, also has Downs syndrome. According to the September 28, 2012 issue of Entertainment Weekly, Trocki was able to meet her namesake although she has advanced Alzheimer's and is expected to be unable to remember her time on the show. According to Gail Williamson of the advocacy group Down Syndrome in Arts and Media who arranged the meeting, when Trocki first met the baby, she said, "I'm your auntie".
- Robin is the fourth character on the show who appears to have Down Syndrome.