Stan grew up in Florida where he went to school until he was about 15. At this time, despite no childhood or current trauma, Stan stabbed a kid with a pencil. He was then expelled. Due to this, he blamed his parents for their lack of parental guidance, taking his anger out on them whenever possible. One day, when Stan was 17, he stabbed his mother in the throat while she was asleep. Luckily.. She survived, and Stan went to jail. When Stan was 20, he escaped from jail and illegally emigrated to Chernarus. He's been here for a while, and once the apocalypse hit.. He decided he no longer had to restrict himself.
Stan has been getting urges since a while before the apocalypse, which is why he was constantly in the hole while in prison. These urges aren't normal and will probably end up killing Stan later on. Imagine.. Starving. You have no food, no water. Your body is shutting down and you're in extreme pain. Well, Stan feels like this randomly throughout the day. He's hungry even though he eats regularly. He's extremely hungry.
Stan robbed a man with his Brother not one week into the apocalypse. They played horrible games with a horrible man who pretty much deserved what happened to him. This man, before he was killed, left Stan with a necklace, a necklace with a finger attached to it. A thumb. The man, before he was shot dead, told Stan to complete the necklace. Said it would keep his urges at bay. Well that's what Stan is going to do. Complete the necklace.