Marcus doesn't survive the Arqueiro and leaves Xena destroyed. Xena organises a funeral where she sings a beautiful song dedicated to the amor of her life.
Marcus discovers that Xena has betrayed him, but as a final act of kindness, touched por Xena's words, he is killed por Mezentius whilst trying to save the princess.
Marcus confesses to Xena that he tried to leave this world full of murderers and mercenaries, but he failed badly. However, Xena sees goodness in his words and she gives in to who was her lover as she still has feelings for him.
This one we really got to see how Xena used to be and how much she has changed. I really liked Marcus, but I am not at all surprised por his death. At least he went out like a hero.