Question about the plot to The Mission (1986).

SPOILER

Why did Phillipe challenge Rodrigo to a sword duel? Rodrigo saw Phillippe with the woman he was in love and then got upset that she left him for Phillippe, and left. Phillipe came out to talk to Rodrigo but Rodrigo walked away and didn't want to talk to him.

Then Phlippe challenges Rodrigo to a sword fight? Why? Phillippe was free and didn't have to right Rodrigo so why did he do it?

I like coffee.

Because it was clear that Rodrigo was going to pick a fight with a stranger on the street rather than deal with his brother.

But why didn't the brother try to talk him out of fighting someone on the street, rather than actually get into a fight?