While Fernand Mondego only appears in the first and last parts of The Count of Monte Cristo, he remains a man interested in his own self-interests. Having disposed of his rival in love, Edmund Dantes, by conspiring with Caderousse and Danglars as they implicate Dantes as a Bonapartist, he convinces the inconsolable Mercedes to marry him. Then, as Dantes is taken to the Chateau d'If on a life sentence, he goes off to war in order to absent himself from any controversy as well as to advance himself.
It is not until Monte Cristo effects his final subterfuge against his last enemy that Ferdinand's name reappears in Chapter 86. His reputation is destroyed as Monte Cristo has a report of de Morcerf's subterfuge of Ali, Pacha of Yanina, whom he has sold his benefactor to the Turks.
Ferdinand, Count de Morcerf exhibits no moral reasoning; he determines wha is right or wrong based upon how a situation advances his personal and selfish interests. Indeed, his moral choices as defined by Kohlberg are personal choices; Ferdinand is an expedient man. For, he has aligned himself with the wealthy Ali Pacha, flattering him and ingratiating himself with the wealthy ruler until Pacha adopts him also as a son. Then, he betrays the Pacha, who has entrusted his ring to him, and sells his wife and child into slavery. After he is exposed,
...he could not have been more overwhelmed if a thunderbolt had fallen at his feet and opened before him an immense gulf.
Ferdinand cannot stand the loss of his prestige and commits suicide rather than face the humiliation of disgrace and imprisonment.