Before Camp Green Lake
Brian was sent to Camp Green Lake because he was trying to steal a car by hot-wiring it.
At Camp Green Lake
Brian came to Camp Green Lake for stealing a car. He came two days after Hector Zeroni (Zero) supposedly ran away. Brian was nicknamed Twitch because he twitches and fidgets a lot. When Stanley wants to bring Mr. Sir's water truck to Zero, Twitch teaches Stanley how to hotwire the truck which Stanley eventually crashes into a hole. It is noted in the book Twitch seems to be supporting Stanley in driving the truck.
After Camp Green Lake
It is unknown what happend to Brian after Camp Green Lake.