He is infatuated with Roxane, the heroine of the play, and tries to arrange her marriage to the Vicomte de Valvert as a "front" in order that he (the Count) may become her secret lover.

When Cyrano kills Valvert in a duel, De Guiche becomes more open in his desires and tries to arrange his own marriage to her.

At Arras, however, de Guiche shows gallantry toward Roxane and a willingness to sacrifice his life to protect her after she arrives at the battlements.

[2] His younger half-brother was Philibert, comte de Gramont (1621–1707), renowned for his memoirs describing the love affairs of the English court of Charles II, edited by Antoine Hamilton.

They had four children: According to Count Philibert de Gramont, their father, Antoine II de Gramont, viceroy of Navarre, was assumed to be a bastard child of king Henry IV by Diane d'Andoins, knowns as "La Belle Corisande".