Although he is not one of the three title characters, d'Artagnan is the story's classic protagonist hero with grand aspirations to prove his bravery. He is an impressive swordsman who values chivalry and is quick to fall in love. Growing up a Gascon nobleman, he leaves his refined but humble roots for Paris. He hopes of finding glory by joining the musketeers, the king's trusted guard. After a series of coincidental incidents, d'Artagnan finds himself dueling with the king's three most famous musketeers, Athos, Aramis, and Porthos, whom he has long admired. D'Artagnan impresses the men, who ask him to join in their fight to protect the king and queen against the corrupt Cardinal Richelieu.
Athos is a superior man and musketeer in nearly every respect. Of noble birth, he is the eldest of the four men, though still young and fit. He approaches his role as a musketeer with a determined sense of justice and pursues those who wrong him with a vengeance. Time and again, Athos proves himself to be intelligent, brave, not to mention an admirable swordsman, and d'Artagnan looks up to him more and more with each heroic gesture. Ultimately, Athos becomes a mentor to the young man. However, beneath his mysterious exterior, Athos is a man tormented by a dark past, which eventually revisits him before the story is over.
Aramis is the youngest of the original three musketeers. Like his colleagues, he is daring in the face of danger and committed to serving French royalty. However, Aramis continually insists that as soon as the queen provides an heir to the throne he will leave the musketeers to become a Catholic priest. When he is not fighting the corrupt efforts of Cardinal Richelieu alongside his fellow musketeers, Aramis studies theology and secretly reads letters from a mysterious mistress with close connections to the queen.
Though valiant and courageous like his fellow musketeers, Porthos values the comforts provided by wealth more than his fellow swordsman. He likes gaudy yet regal clothing, good food, and the attentions of rich women. He is vain and brash, but also a lovable comedic force. Porthos ultimately gives up his duties as a musketeer to marry his wealthy mistress, who inherited a fortune from her late husband.