He was a poor Catalan fisherman in his youth. He was in love with Mercédès, Edmond Dantès' fiancée. He mailed the letter accusing Edmond of treason to Monsieur de Villefort which led to Edmond's arrest.
A few days before the second Restoration, he took part in the battle of Ligny. The night of the battle, he acquantinced with a general who was in secret contact with the enemy. The general persuaded Fernand to accompany him and join the English. Upon return to France, Fernand was made a lieutenant and became a captain by the time the war with France began. Successive military achievements, with the help of Danglars, who lived in Spain at the time, gave him the promotion to colonel, after which he was named the Count de Morcerf.
He served in Greece under Ali Pasha, who rewarded Fernand by bequeathing him a large fortune. He betrayed Ali Pasha and sold his daughter into slavery. With his new fortune, he settled in Paris and married Mercédès, with whom he had a child. His downfall begins when the Count of Monte Cristo reveals Fernand's trecheraous acts against France and Ali Pasha to the press. When he discovers his wife and son have abandoned him, he shoots himself.