Isaac Foster prefers to be known as Zack because he thinks his proper name is 'too prissy'. He is irreverent, childish and rude, despite being 20, and swears copiously. He hates liars and being called a 'tool' with a passion, wanting to do things on his own terms. Despite his angry exterior, he has a big soft heart for people he trusts. He wears bandages due to being burned as a child and is terrified of fire. He is illiterate and not very bright, but street-smart. He is also a serial killer.