Sonia and Manic were first greeted by Bellok upon their arrival at Worst Castle. Bellok showed the two hedgehogs their rooms, but they were overrun with bats and rats, frightening Manic out of his wits. Later, while Sonic was searching Worst Castle after Sonia told him she had seen their mother, Bellok spoke behind his back and unintentionally shocked him. Sonic was displeased with Bellok for not appearing earlier to show him his room, and when he gave Sonic directions, they were long and convoluted. Shortly after Bellok left, a rope holding up a chandelier snapped and Sonic was nearly crushed, causing him to suspect Bellok of being an enemy.
Sonia was later found to be missing, and when Bellok showed up in the corridor, Sonic pursued him and demanded an explanation as to what was going on. Bellok initially refused to say anything, but was coerced into doing so by Sonic's noisy guitar music. Bellok revealed that he had been forced by Sleet, who threatened to eat his owl Hooter, into helping him set a trap for the Underground, and that he was on his way to the castle with Dingo and his Swatbot. Sonic understood and agreed to help stop them.
Bellok confirmed that he was an agent of Queen Aleena and that she had told him about the special mirror in the castle, which he described as a "portal to different places". He allowed Sonic to venture through and retrieve Sonia from the mirror. Shortly after the hedgehogs were reunited, Bellok warned them that Sleet and Dingo had arrived. He also informed them that each room contained a trapdoor, and the team used this to their advantage in order to defeat most of the Swatbots.
Near the end of the episode, when Worst Castle was under fire, Bellok entered the mirror with the hedgehogs to escape the turmoil. When the mirror shattered, he was warped outside with the others and watched the destruction of the castle. He believed that Manic's dream (in which Queen Aleena said the mirror was the way out) was real, and sure enough it was, as he acknowledged the presence of Aleena nearby.
Bellok is very benevolent, although he cannot stand loud noises. He has a pet owl called Hooter whom he is very fond of. His catchphrase is "I am Bellok, the castle caretaker", and he speaks with a classic Eastern European vampire accent.