Carlos was a bodyguard for several high rolling individuals back in Australia. He was gifted in pistol skills as well as Melee. He came to Chernarus on a holiday with his long time partner. Who he forgot about after being struck with a baseball bat to the skull in the early days of the outbreak. Its better that way for him so he doesn't have an attachment to anyone which makes him better suited for this environment. Which is harsh and unforgiving and making attachments in this day and age of the outbreak is dangerous to not only him, but everyone else around him.