Sardonyx

Grey Matthews (aka Sardonyx) is the head of the 24-K family and was Dr Edwin Heidegger's servant for 25 years.

He was an assassin in his earlier life, and had killed Spiddrelli's wife. Spiddrelli in turn promised him 'an eye for an eye, and a heart for a heart,' and was subsequently executed. He favors decapitation, as seen in Louie's brainwashing and Spiddrelli's execution.

He has been trying to steal the technique to Psydiving from the Heidegger family to sell it, and practiced brainwashing on Louie. He brought Garnett to Midvale in order to have him set up a surveillance array of cameras throughout the island.

He becomes fearful and delusional after seeing Spiddrelli once more on camera footage and fears that he will kill his daughter Topaz because of what he did to Spiddrelli years ago. He and Garnett plan to fled the island, kidnapping Gywnn in the process believing her to be Topaz and set sail on a boat sailing away from the island. He than proceeds to act like a pirate and sing and dance with the unwilling Garnett and Gywnn.