"Onion" is a minor character in Steven Universe and a resident of Beach City. He made his debut in "Laser Light Cannon" as a cameo character. As revealed in "Onion Friend", he is the son of Yellowtail and Vidalia and the half-brother of Sour Cream.
Onion is a fair-skinned boy with a small tuft of blonde hair and a chubby face. He wears a white sweater, a deep periwinkle shirt tied around his neck, and pale red footie pants. His most recognizable trait is his onion-like head (although the top is thinner than the bottom, not resembling a normal onion). He also does not have any visible ears.
Onion is a very quiet kid who chooses not to speak to anyone except for his parents. When he speaks, it sounds like gibberish. Despite this, people seem to communicate just fine with him, showing no confusion whatsoever. Onion is eager to help people. He will blindly follow orders even if they don't seem very well thought out, such as in the episode "Bubble Buddies", when he shot a harpoon at Steven's bubble. He cannot stand being lied to, especially by close friends, as shown in "Steven's Lion".
He has been seen to be a thief in "So Many Birthdays", as he was seen stealing tickets from an arcade machine, which explains how he had enough to win a moped in "Arcade Mania". This is further emphasized in "Onion Trade" with Onion's delinquent behaviors such as destroying the moped for no apparent reason. He also stole Steven's Chaaaaps and Ranger Guy in the episodes "Onion Friend " and "Onion Trade ", respectively. Onion's delinquent and kleptomaniacal behavior can be attributed to his severe loneliness as a grab for attention, due to his father constantly being at sea. He does not seem to understand or simply not care when and if he is hurting people, has no qualms with stealing what he wants, and does things obliviously in the name of fun. This could be attributed to his young age and lack of moral understanding. He continues his bad acts in "Watermelon Steven", when he steals Steven's Baby Melon despite Steven stating he wasn't for sale. In "Political Power", Onion seems to be on the verge of attacking Mayor Dewey as he held his baseball bat menacingly.
He has also been shown to have a rather strange fixation with food, in that he is never seen eating it but instead throwing or destroying said food as said by Steven and proven in "Onion Trade" and "Onion Friend". He seems to have an overall strange personality, as he is a very difficult person to understand and predict.
Steven is Onion's friend whom he has known in the past and is eager to help. They may get along, but it is a one-sided relationship as Onion isn't known to talk to anyone but his father and his mother. However, his mother says that Onion talks a lot about Steven. Steven seems to wonder what Onion is doing most of the time. In "Onion Friend", Onion seems to do certain actions specifically to push Steven's buttons as a form of childish teasing, wasting food intentionally knowing that it bothered Steven and pretending to feed a mouse to his pet snake in order to scare him. He also seems to steal from Steven pretty often, from his Ranger Guy to his bag of chips. Onion however, is shown to care about Steven as he gave him his Explorer Gal as well as show him his collection of G.U.Y.S and G.A.L.S in Onion's secret room.
Onion doesn't see his father often due to him being at sea most of the time, and this causes Onion to spend a lot of time wandering around, unsupervised. When Onion does see his father, he has been shown to speak to him in an unknown language. Yellowtail is one of the people Onion has been shown to speak to.
Vidalia, his mother, shows a very close relationship, with her being the only other person he talks aloud to, albeit just the word "mama". She also encourages his expressive nature. Whether she is aware of Onion's strange and unnerving activities is currently unknown.
Onion and Connie have only met once in "Bubble Buddies", but Onion has been shown to be able to understand Connie easier than Steven, shown when she spelled "Harpoon Gun" on the bubble shield they were trying to pop, while Steven attempted to draw one.
Onion and Sour Cream have never been seen interacting, although they are shown together in the evacuation of Beach City in "The Return" and the opening theme. In "Joy Ride", it was confirmed that Sour Cream and Onion are either half-brothers or step-brothers. Explored further in "Onion Friend", it was confirmed that they are half-brothers.
In "Onion Trade", Onion enters Suitcase Sam's business and is given a hamburger by him, for unknown reasons. They may possibly be friends, given Suitcase Sam's giving Onion a hamburger. He also has a poster of Suitcase Sam on his wall in his room; revealed in "Onion Friend".
- "Laser Light Cannon" (debut, cameo)
- "Bubble Buddies"
- "Steven's Lion" (cameo)
- "Arcade Mania"
- "So Many Birthdays" (cameo)
- "Onion Trade"
- "Rose's Room" (cameo)
- "Ocean Gem" (cameo)
- "Garnet's Universe" (pictured)
- "Watermelon Steven"
- "Marble Madness" (mentioned)
- "Political Power" (cameo)
- "We are the Crystal Gems" (cameo)
- Onion is seen behind Connie in the original intro where Mr. Smiley stops him from running out into traffic.
- He can also be seen on the roof of The Big Donut in the second intro.
- So far, Onion has only communicated with his dad and mother, and all of his dialogue has been unintelligible mumbling.
- Rebecca Sugar first hinted in a Reddit AMA that Sour Cream and Onion are related. "Joy Ride" later depicted Sour Cream referring to Yellowtail as his stepdad, and "Onion Friend" confirmed that Sour Cream and Onion are half-brothers. This makes them a play on "Sour Cream and Onion", a popular flavor of potato chips.
- Steven has been shown to doubt if Onion is human in "Marble Madness".
- Onion seems to have a phone, despite that he has never been seen to speak to anyone other than Yellowtail and Vidalia. It's shown that Steven has him in his phone's contact list in "The Return".
- As Onion understands English, it is possible that he and Steven can communicate more easily through texting.
- Onion owns a pet snake, which he tries to get Steven to feed with a mouse found in his room.
- In the comic story Lion Tamer, Onion is seen at a pet contest walking a pet alligator.
- Onion owns an impressive collection of both toy G.U.Y.S. and G.A.L.S. which includes a Red Variant of Ninja Guy, Hardhat Gal, Triangle Gal, Orange Gal, Karen, and Explorer Gal which he proceeds to give to Steven.
- Onion owns a poster of The Door in his room; an obvious reference to the 1965 rock band The Doors.
- Onion is described as "???????" in "Rising Tides, Crashing Skies" while being interviewed.
- Similar to how Dave Guy might be a reference to Dave Strider from Homestuck, Onion's characteristics, such has his apparently creepy personality, relationship with his sea-faring father, and quiet nature, may be connected to Kurloz Makara, who is another character from the webcomic. However, this may only be a coincidence.