When I come to the mercenary captain I have to beat him, But I don't have the option to challenge him on a duel, I paid to the guards and they said that they dont like the captain, How I get this option of making him fighting his own battles?

ermm i think you shoudld say erm.. work for him

 

 

 

then bla bla bla he tee\lls you to get the head of some dude

 

 

 

go west to a camp and talk to their leader

 

 

 

the" hello effendi "guy

 

 

 

 

 

 

 

then talk to the captain again

 

 

 

 

 

 

 

then FIGHT!