This time, Thirteen was about to fight a teenage Barbarian boy who was around fifteen years old.
He wasn't a slave. On the contrary, he was one of the young Barbarians who enjoyed fighting against them.
For them, fighting slaves was a good way to train themselves and was more effective than looking for Monsters to fight in the wild.
In fact, many young Barbarians do this, and this gained the approval of the adults.
Since killing wasn't allowed, and he was a Barbarian, Brakka was able to get special treatment, allowing him to fight opponents who were weaker than him.
He was the Duel Arena's 'Cleaner', whom they'd call up in order to deal with the troublesome slaves who had offended many people.
Since the Barbarians wanted to see Thirteen suffer and bleed, they pressured Raldo to make Brakka the boy's opponent if Jubei wished for him to fight again.