“Despite his cartoon villain spiel and bizarre hobbies, Caliborn can be quite clever. He enjoys deploying "shitty" twists to spoil his "opponent's" game (such as pretending to switch positions of two chess pieces but merely camouflaging them as each other), and could be quite threatening if he was not so obsessed with theater.”

(Taken from the Homestuck Wiki)

I’m imagining more of a raspy voice, he would have a higher-medium tone in his voice, and sound a bit more childish than most teens.