In his first appearance, he stumbled upon an unmasked Black Mage and passed out after seeing his "insane, non-Euclidean face", and shortly after waking up again he passed upon a group of guards killed by Black Mage. Later, his family was kidnapped by Black Mage while camping in Elf Land so the Light Warriors could use the bodies to deceive the elf ninja guards who killed them. His first foster family was killed by Black Mage after the Light Warriors returned from Gurgu Volcano, and were solving the mystery of Crystal Lake. Some time later, Black Mage used his Hadoken to destroy a ship filled with food and medicine destined for the kid's community of orphans, Onion Kid was expelled due to his tragic back story. His second family died after a complaining old man was thrown by the Light Warriors off their airship, sometime after their passage on the Castle of Ordeals. The death of Onion Kid's second family led him into being judged for murder. More recently he has been seen apparently teamed up with Dragoon and White Mage. Even more recently, it seems that he
has been kidnapped by is a past version of Sarda. Sarda sent himself to wizarding school, and after many years of training, becomes the most powerful wizard in existence. He sends himself to the beginning of time to remake the universe so that the Light Warrior don't exist, but White Mage foils his plans.
- In the fancomic Episode 700.1: Ripped From Today's Headlines, it is revealed that Onion Kid is named "Rex Crockett." However, it is widely agreed, especially on the Nuklear Power Forums, that this is not canonically true. Brian Clevinger (under his forum name, Kurosen) has explicitly stated as much, since "I like his name being unknown to the audience."