Than asking how he knew? I think our brother may have tipped him off. Or the concubine. Or whoever it is wants our bodyguard dead for foiling there attempts on our life.
How he knew what? Barrick didn't directly stop us dying, and it's unlikely too many knew he paid people to protect us.
This is how I think the whole duel thing should go down:
Call him out for cowardice. Hint you want him to withdraw. Don't directly tell/ask him. E.g. "..... and on top of that you say you'll only withdraw is if my best bodyguard is locked up? Right after I was nearly KILLED when he wasn't around?"
If that doesn't work:
Challenge HIM to a duel for Serles. Real weapons, first to draw blood, no maiming or killing. Keep the duel private. Play it like you're doing it out of gratitude for his saving your life, and that you'll show what happens when you're facing your opponent head-on. This'll stop Serles from looking like he needs to be protected. He's bigger and stronger than us so best to use our Youthful Agility to its maximum and to keep dodging attacks. We may not be able to block too many. It would also be fun to see how combat would be like in this game (turn-by-turn, beginning-to-end, etc.)
If he refuses that too:
Accept the duel to the death. Appoint Varick of the Silver Moon Company as your champion. In this case make the duel more public (no rabble, just nobles). He has the best chance out of anyone at beating him, there's little political repercussions if he loses (he's just a merc after all) and nobody important dies (there are other mercs in the company who can take his place). If he wins the matter is settled and our merc company looks awesome and we can increase its clientèle. We also get to see him use his bitching claymore. If tournament duels
aren't covered in the mercenary contract (they should though, I think) then offer him a small reward if he wins and pay his medical bills if he's injured. If he loses, he's dead, and we pay nothing. Heck we may not even have to pay it out of our own pocket. Just throw it in with the tournament expenses or something.
Mlamlah, are dirty moves such as spitting and throwing sand in a duel considered cowardly? If it is then we might still get away with it what with being 13 and all.