D’Artagnan has a command position. Porthos marries Madame Coquenard the following year.
Aramis retires into an unknown convent.
Athos remains a Musketeer under D’Artagnan’s command until he inherits property.
D’Artagnan and Rochefort fight three times. D’Artagnan wins each time. On the third time, D’Artagnan points out that he will likely beat Rochefort if they fight a fourth time. The two of them embrace as friends.
Monsieur Bonacieux continues to live quietly without a wife. One day he has the impudence to assert himself as a friend of the Cardinal, who tells him that he will be provided for the rest of his life. Monsieur Bonacieux was never seen again; his neighbors believe that he’s probably in a royal castle living on the Cardinal’s dime.