how does dantes seek revenge against Fernand

Fernand was the fisherman who betrayed Dantes because he was in love with Mercedes. Military glory brought him a fortune, and he changed his name to Count de Morcerf. He commits suicide after Monte Cristo reveals his military treason. He betrayed his benefactor in Greece, Ali Pasha. He surrendered the Greek city to the Turks, and sold Ali's wife and daughter into slavery.