Because there's nothing quite so fun as a crazy transgenic--and an evil twin storyline, for good measure. Isaac was Joshua's younger brother--"smaller, gentle"--who Sandeman had told Joshua to protect. Isaac was Father's favourite, and didn't take his departure well. He spent his time wailing for Father, which annoyed the guards to no end. When Isaac wouldn't stop, the guards restrained Isaac and cut out his tongue.

This left Isaac with some deep psychological issues. The police reminded Isaac of the guards as Manticore, and Isaac responded by ripping their tongues out. Two cops had been killed, and a third was alive but without his tongue in the hospital. (The missing tongues were hanging from a clothesline in Isaac's hideout).

Joshua was trying to help his brother, but Max stepped in to deal with everything herself. Joshua and Max found Isaac who proceeded to attack Max. Joshua ended up stabbing his brother with a pipe, killing Isaac.

Isaac was buried at Joshua's (formerly Sandeman's) house. His grave was marked by a piece of concrete. Joshua mourned, remembering that "Father said, 'protect him.' I tried."

Isaac appeared in Two.