Rattles is a fourth grader at Lakewood Elementary School, and a member of the Tough Customers.
Rattles has a tuft of hair sticking out of his red baseball hat, which he always wears backwards. He wears a black leather jacket with two pockets at the front; a pale yellow T-shirt; green jeans and high tops. In the first seven seasons and the ninth season, his tuft of hair was dark brown. For the eighth season, his tuft of hair became gray like the rest of his body. In the tenth season, this change became permanent.
For his alternative outfit, he wears a dark blue T-shirt over a pale yellow sleeved shirt instead of a T-shirt and leather jacket.
In early seasons, Rattles started off as a tough, generic school bully. After he got an expanded role in Season 8, he becomes the most consistently antagonistic force in the show, with his directly malicious and petty behavior. However, like his friends Binky and Molly, he started displaying a softer and more intelligent side, with his own personal hobbies that he (secretly) enjoys.
In the episode "Bugged", he is seen with the other kids at the playground playing marbles. This shows Rattles does indeed hang out with other kids in the school despite being a bully.
He has helped D.W. on a few occasions; in "D.W., Dancing Queen", he and Molly helped D.W. do ballet for a school project after Binky twisted his ankle during practice, both serving as D.W.'s backup dancers. In "D.W., Queen of the Comeback", when the Tibble twins start teasing D.W. over her botched haircut, Rattles tries to come up with good insults for D.W. to use against them, though he thinks their feud is ridiculous and initially suggests to D.W. that she ignore them.
He seems interested in knitting. For example, he is a member of Dr. Fugue's knitting club in "Arthur Unravels". Also, it is mentioned throughout the series, though more recently than before, that he is skilled at sewing.
In the episode "Brain's Chess Mess", Rattles reveals he is a skilled chess player, able to beat Brain quite easily, and tutor him and the other members of the Chess Club.
In "Carl's Concerto", Rattles willingly helped George and Carl rehearse for a children's puppet show, alongside Buster and Binky; he played as Mama Bear in George's "Goldilocks and the Three Bears" play. Although Carl's autism made rehearsals difficult, Rattles willingly put up with it without complaint until the day of the puppet show.
Interestingly enough, he doesn't seem to consider himself a bully or at least does not like the label. In several episodes when other characters refer to him as such he counters by saying that he's just "misunderstood". At several points, he also seems to be smarter than he appears, sometimes using shockingly advanced words to describe or explain something; however, as revealed in "D.W., Queen of the Comeback", he doesn't know the definitions of some of said words, such as "bibliophile", and thinks they make good insults. When Brain offered to do his homework for a month in order to get him to join the Chess Club, he refused by saying that it would deprive him of his education. This could show that like Binky his tough guy personality is just for appearances or to cover up his other hobbies.