Capper is an anthropomorphic cat, and once one of the workers under Verko within Klugetown.
Personality
Capper is portrayed as smooth-talking, streetwise, and opportunistic, able to charm others with his charismatic personality and quick wit. He initially sees Rarity and Applejack as a means to settle his debt, but after Rarity's show of generosity, he chooses to help them by helping them escape Verko's airship.
History
Capper once was a pickpocket and thief alongside his friend Chummer, before they arrived in Klugetown. When there, he and Chummer were given a home and decent pay by Verko, and was offered to work for him. Capper agrees, though got into a disagreement with Chummer that broke their friendship because of it.
Season 7
He first appears when the ponies Rarity, and Applejack, attract too much attention from both Verko and his goons. Capper "scares" them off by claiming the ponies are infected with the fictional pastelus coloritis. He then offers to serve as the ponies' guide and protector through Klugetown on their way to find Rockhoof's Shovel, but he secretly makes plans to sell the ponies to crime boss Verko in order to settle his debt. At first Applejack doesn't believe him, but he gains her trust by presenting the actual shovel back in his place.
Capper charms then, and while Applejack was away, Rarity surprises him with a generous gesture as thanks for helping them. Rarity then asks him about Chummer, to which he dismisses as being some other cat, and denying him being friends with Chummer since he refused to join him in working for Verko. Verko appears, exposing Capper's true dishonest intentions. At first he wasn't willing to help, but after talking to Chummer and learning he wasn't going to ever pay his debt, he decides to go and save them. He tricks Verko by insisting Rarity and Applejack needed to take a bath, thus taking them out of their cage. He then distracts Verko for a while until they were safe, backstabbing Verko and leaving him. He and Chummer then go off to start a new and better life together.