San was born with a gift, which makes him special. Until one day he was trapped in a "The Glade" along with few other guys for an experiment. San escaped though, along with few other guys which was Hongjoong, Yunho, Mingi, Wooyoung, Jongho and Yeosang. Just as they thought they were free, they found themselves being in a place called WCKD, also the same group of people that trapped them at The Glade. At first they thought it was a safe place for them, until they realised that it was not. So they ran far away from the place where they thought WCKD wouldn't find them. Then when they were at a secret, hidden place where they thought it was the Right Arm base, they met Seonghwa, and you. Sure, at first Seonghwa wasn't that pleased about them, but then he discovered that they were are special, especially San. So he helped all of them to find the Right Arm, but before they all could even escape the base, WCKD found them. While everyone is already by the secret door to escape, San was worried about you because you weren't there yet. So, instead of getting out, he went back in to look for you.

"Hey, what are you doing here? We need to go now!"