Onion was first teased by Cabbage in Excess Cabbage, but, later laughed at him along with Celery and Orange. After Cabbage was chopped to pieces, Onion tells Orange that he was sorry about Cabbage's demise. After Orange thanks him for that, he explains that people never know when their time is up, but is interrupted when he is unexpectedly sliced in half, proving his point. Another onion (voiced by Dane Boedigheimer) appears in the Cursed Onion Ring Tape episode where he also gets knifed, but then turned into an onion ring. In Food Court, a third onion appeared that was portayed by Peter Coffin too. However, there were differences in the lip color and voice.
Onion is the first of the few characters to die with someone else in a episode, Cabbage to be precise.
He was on Pear's space, where Pear is always sitting there.