After Woody, Buzz Lightyear, Trixie, Rex and Angel Kitty enter the Battlesaur playset, Reptuillus Maximus welcomes Rex and Trixie in their quality of being dinosaurs, while completely ignoring the three other toys. He starts to fall for Trixie, which he finds "quite unlike our females", and makes her visit all the parts of "Battlepolis". However, he does not understand Trixie when she talks about toys and play, stating that he would not accept to "surrender".
Reptillus shows off his gladiatorial prowess in the Arena of Woe by "slaughtering" the toys captured by the Battlesaurs. He is puzzled, however, when Trixie attempts to stop him. In the process, he discovers that Trixie has the name of Bonnie under her foot, which he and the Battlesaurs consider to be a sign of surrender. Reptillus feels deceived by Trixie and expresses bitter disappointment of her.
He chases Trixie when she flees to bring in Bonnie and Mason and gets out of the Battlesaur playset. In the process, he stumbles upon his own box. He is horrified by this finding, but refuses to face his reality and knocks down the box. He prevents Trixie from turning off the power of Mason's video game console and confronts her. Trixie convinces Reptillus of the greatness of being a toy. Reptillus finally accepts to surrender and lets himself be picked up by Mason and be played with, so he is transformed by the experience. During the credits, he expresses his hope to see Trixie again.