Xo was a member of The Fleas, a group of young thieves from Flea Bottom. He was a slim boy with black skin like that of the Summer Isles.
Xo is among the handful of Fleas who confronted Cleos Baratheon in the streets of Flea Bottom, suspecting him of being in a rival street gang led by a boy named Brave Ben. Cleos managed to scare them off with his castle-forged steel.
When Cleos joined the Fleas, Xo taught him the art of lock-picking.
During a raid on the gold cloak's armory, Xo set a building on fire in order to distract the gold cloaks.
Xo was captured and tortured by commander Titus of the gold cloaks, eventually giving away the location of Sanctuary, the Flea's hideaway. After he had given away this information Titus killed him.