The symbol on his cheek was the symbol of his group. When he became a full member he was marked like the rest of the members. It was sign of bravery, and loyalty.
Cooper never had many freinds when he was young, it got worse when his mom died. He was bullied as an orphan, because he had the powers of a cipher, but he couldn't use them. This angered him so every night he'd sneak out of the orphanage and practice harnessing his powers. Eventually he had them controlled. The next time he was teased he fought back. Not realizing how strong the powers were he nearly killed the bullies. He knew he couldn't stay after what he'd done. He ran and ran until he couldn't anymore. He eventually collapsed in a dark alleyway deep into the city. He was found by a group of exiles. When he woke up to see the group he was surprised and accidentally used his powers on a member of the group. He thankfully missed, but it turned out the group was actually a bunch of exiled kids who had cipher powers too. Cooper fit in to the group and they mentored him in how to use his powers to his advantage in heists. They were like a family, they always had each other's back's. They cared for each other. Until one day when they ran a heist against someone they underestimated. The so-called person called himself "clockwork". The group was massacred they managed to save Cooper from Clockwork's twisted grasp. The last thing the leader said to him before taking his last breath was "you're going to go far kid...". Ever since then he's been training, and running his own heists hoping one day he can face the malicious Clockwork and avenge his freinds.
