Barrel is undeniably the weak link in the trio, not being as competent as Lock to assume leadership, or as clever as Shock to create plans of tomfoolery. As such, he is often bullied by the other two, and struggles to stand on his own two feet to prove that he can keep up with them. Though dressed as a make-believe skeleton, he certainly isn't just a pile of bones.
When they're not pulling pranks on the townsfolk, he, Lock and Shock act as Oogie Boogie's eyes and ears, informing him of the who, what, where, when, why and how with everyone and everything that's going around in town. He and his cohorts overhear Jack telling Sally about the heart he's making, and go off to tell Oogie about this new revelation. They steal the heart from the laboratory, and after delivering it to him, initiate a battle in their playroom against the party to prevent them from proceeding further.
A third of the trio of child miscreants, Barrel is the shortest and roundest of the three, and also the clumsiest, often prone to tripping over his own feet. He covers his face with a round mask that depicts the face of a smiling skeleton.
Barrel along with his two playmates Lock and Shock spends his days in Dr. Finkelstein's laboratory where said doctor is building him and his friends a plaything, later known as The Experiment. Barrel and friends are later hired by Maleficent to cause a ruckus in Christmas Town; once this fails and once Maleficent resurrects their evil master Oogie Boogie from the dead, Barrel and his pals are given dominion over a cage Heartless whose element changes according to the person inside its cage. In this case, Barrel symbolizes ice. Unfortunately for Barrel, this will be the last of his fun for a while and so he and his peers sift through Santa's toys for parts for their would-be plaything. Fun comes along again soon as Sora and friends accuse them of stealing presents - of which they are innocent - but alas, they are whipped back into shape and Barrel runs away with his tail between his little legs.
While Lock and Shock are the masterminds behind the trio's plans, Barrel is often just going along for the ride, although he has the same appetite for pranks as his fellow tricksters. Being a little slow and clumsy makes him the butt of the other two's practical jokes and causes him to be the blame for all the crimes the trio has committed. He has a tendency to blurt out the trio's latest plan, but unfortunately Lock is there to keep an eye on his mouth.