Sadie Miller is a supporting character in Steven Universe. She's supportive of Steven's adventures, if only to make Lars angry.
Sadie is short and heavyset, with curly blonde hair. She acquired a small, barely noticeable facial scar in the episode "Island Adventure" when the Invisible Gem Monster attacked her.
She works at the Big Donut, so she is usually seen wearing the uniform. Her uniform consists of a periwinkle polo underneath a purple shirt, which displays the Big Donut logo (an image of a half-eaten donut that resembles the letters "B' and 'D'). She wears black leggings and pink-red shoes. Her casual outfit is a dull pink jacket, green shirt, black leggings and pink-red shoes. In "Island Adventure", she wore a black shirt, then a few days later, she wore Lars' shirt, which has a picture of a snake on it. In "Change Your Mind", her hair is dyed green, but in Steven Universe: The Movie, her hair color is returned to it's natural hair color.
Sadie is a clerk at the Big Donut and works with Lars. She is friends with Steven and enjoys his comebacks. Although she is friends with Lars, she doesn't like it when he makes fun of Steven.
Sadie has a crush on Lars, as confirmed in "Joking Victim". At times Lars can be a jerk to Sadie and be lazy, snobbish and rude towards her. Although, in "Island Adventure", he showed extreme affection towards Sadie, even going so far as to kiss her. Though the two constantly go through a love/hate relationship, (Steven once called them "married" in the episode "Coach Steven"), they are shown to be good friends and are almost always seen doing things together as shown in the episode "Tiger Millionaire", at the end of "Steven and the Stevens", at Beach-a-Palooza, watching the play together put on by Steven and Jamie in "Historical Friction", and in "The New Crystal Gems", where they were sitting on a bench close to each other. In "Sadie's Song", Sadie panics about performing at Beach-a-Palooza when she sees Lars in the audience. In "The New Lars", Sadie is annoyed that Lars would rather hang out with Buck Dewey than her. Sadie is later surprised to see Lars (without knowing Steven is in his body) show up at her house. She picks up on the fact that Lars is acting different, wanting to watch a romantic movie, him being kind to her, and she thinks wonders why Lars does not want to be seen in public with her. As Lars, Steven confesses Lars' love to Sadie which prompts Sadie to kick Lars out of her house because she thinks that he would do that to upset her. When Lars returns to his body and is working at the Big Donut, Sadie comes into work and accepts Lars' offer to hang out, leaving Steven to know that the two love each other. In "The Good Lars" she tries to help Lars be more close to the Cool Kids only for being dissapointed that he doesn't come and admits that she can't change Lars, it culminates in "I Am My Mom" when Sadie after being capture by a Topaz she asks Lars for help only to look how hides in fear much to her disapointment. In "Change Your Mind" after Lars finally returned to Earth, she and Lars reunited and reconciled their relationship.
Lars is seen to get jealous over Sadie, as in "Horror Club" when he attempts to one-up Ronaldo Fryman after he is seen "flirting" with Sadie - hinting towards him starting to return Sadie's crush.
Sadie thinks of Steven as a close friend, almost acting like a sister, even considering their age difference, she encourages his ideas and tries to help him in any way possible as seen in "Watermelon Steven" where she supports Steven's watermelon business. Even though she does not exactly understand his life situation, specifically related to magic and the Gems, she does her best to support him and she even knows about his mother's sacrifice, as seen in "Lion 3: Straight to Video" where she rushes to help Steven see a video of Rose.
Barbara Miller is Sadie's mother. It is revealed that she cares deeply for her daughter, as shown in "Lion 3: Straight to Video" Barbara still packs lunches for Sadie every day. The two care a lot for each other, though Barbara tends to treat Sadie as a child, which displeases her.
"Sadie's Song" however, focuses a bit more on their relationship. It revealed that Sadie does not feel entirely comfortable with her mother around, due to her overbearing support over everything. Barbara takes any of Sadie's interests to a level in which Sadie is uncomfortable with, such as making her performance as bold as possible, despite what Sadie says. However, Sadie has explained this to her mom, and it is assumed that she is working to get this under control.
Sadie officially meets him in "Horror Club". She treats him as a good friend, while Lars is jealous of their friendship; possibly in part to their falling out in childhood.
- Fishing Skills: As of "Island Adventure", Sadie has become very skilled in the art of fishing. She has fished for Steven and Lars when they got stuck on the island and is able to fight the Invisible Gem Monster with her skills to protect Lars.
- Rebecca Sugar has confirmed that Sadie likes to eat oyster crackers, which was later shown in "Joking Victim."
- In "Coach Steven," Sadie is shown writing in her journal using her left hand, thus revealing that she might be left handed.
- Sadie and Lars were confirmed by Rebecca Sugar to be some of her first ever characters. "Lars and Sadie were old characters of mine, from college!"-Rebecca Sugar on Reddit.
- It has been heavily implied that Sadie has a crush on Lars.
- Sadie's voice actor is Kate Micucci, a singer and songwriter.
- Sadie was shown crying for the first time in "Joking Victim."
- Sadie states in "Joking Victim," that her job at the Big Donut started as a summer job, but that it has been two years since.
- Her personality is similiar to Sans.
- "Little Graduation" marks the final appearance of Sadie.