Arpeggio was the final member of the Klaww Gang that the Cooper Gang confronted in Sly 2: Band of Thieves. While every member of the Klaww Gang played a vital role in the big picture, Arpeggio was the mastermind behind it all. Little did the Cooper Gang know, but everything that happened up until that point was expected by Arpeggio.
Arpeggio desired to attain the same power that Clockwerk had. Arpeggio was such a genius, that the Cooper Gang stealing the Clockwerk parts from other Klaww Gang members was actually part of Arpeggio's ultimate plan. He knew the Cooper Gang would find him, and conveniently bring the remaining Clockwerk parts with them.Arpeggio grew up very smart, but never quite grew physically, remaining a smaller sized parrot. This frustrated Arpeggio, and led him to find a cure for himself using his great mind.Eventually, Arpeggio learned of the infamous Clockwerk, and became obsessed with recovering the Clockwerk parts as a plan to cure himself, as well as make him extremely powerful. Arpeggio studied Clockwerk, and learned of how the power of hatred fueled Clockwerk and kept him alive. Arpeggio decided to learn the mastery of hatred to be like Clockwerk was. Arpeggio's plans were falling in place. However, in the end, he was betrayed by his protegee, Constable Neyla, as she turned against Arpeggio and killed him. Neyla wanted all the power for herself and waited until all the Clockwerk parts were in one place. This led to the creation of ClockLa.