Benvolio must fight.

Benvolio: I do but keep the peace;put up thy sword,or manage it to part these men with me.Tybalt: What, drawn and talk of peace!I hate the word, as I hate hell,all Montagues, and thee.Have at thee, coward!Okay, heartless hinds.We know that once again,it's not a good thing.Both families hate each other,and this is just adding fuel to the fire.But just how bad is this stinger?A heartless hind is a coward,and calling someone that in front of his own men, and the rival family,means there's going to be a fight.Tybalt basically calls out Benvolio,and in order to keep his honor,Benvolio has to fight.