It is unknown how long Atilla had been a pet in the Ferguson family. Since parrots have a Fifty to Ninety year lifespan, they may have inherited him from a deceased relative. Atilla was very close with Calvin and his mother Mrs. Ferguson. He often frequented the families store the Party Animal. They had him sit near the cash register to possibly keep the family company while working or waiting for customers.
He often repeated a lot of what Mrs. Ferguson would say about the boasting and bragging she did about her son Calvin. At times, he would make compliments and remarks about Calvin to the customers. Or back up and support some what Mrs. Ferguson would tell people about him.
He was also known to be the object of ridicule and annoyance for the Ghostwriter Team. In "Ghost Story", he bragged about Calvin to customers in the store. Also Alex made fun of him and pretended to be him when he and Jamal Jenkins prank called THABTO leader Dan.
Also, in the "To Catch A Creep", story arc Lenni made fun of him when she and Jamal asked Rob to go to the Party Animal listen to him and Mrs. Ferguson constantly brag and reveal embarrassing and personal facts about Calvin. When Rob got the information, he mentioned that he would not stop talking about Calvin.
During the events of "Am I Blue?", Jeffrey Baxter revealed that he was away being dipped and treated for fleas. Calvin being ashamed of this fibbed. So Calvin tried to say that he was smart that he was invited over to do a lecture at Harvard University.
Then in the "Who is Max Mouse?" story arc, Calvin told Lenni that Atilla had just passed away. Calvin revealed that he died from an illness. Lenni joined Calvin to give him a proper burial service. Then Calvin sang a tribute song (terribly off-key) straight from his heart to honor and remember him.