Le Bret makes his entrance in the first act to give Christian more information about Cyrano.
Throughout the first act, he hopes that Cyrano will not show up at the play because he doesn’t want any trouble between him and Montfleury.
After Cyrano’s duel with Valvert, he confides to Le Bret that he is in love with Roxane. Le Bret encourages him to tell Roxane, but Cyrano refuses.
After Cyrano meets de Guiche for the first time, Le Bret asks him why he insists on making so many enemies. This brings on one of Cyrano’s first long soliloquies about his honor and his love of freedom. Le Bret sees through this, knowing that Cyrano would rather have Roxane than all the ideals in the world. He pronounces much of Cyrano’s showy chivalry madness.
At Arras, Le Bret keeps watch with Captain Carbon de Castel-Jaloux as the rest of the men sleep. Le Bret is one of the few men who knows that Cyrano risks his life every morning to send a letter to Roxane.
When Roxane arrives unexpectedly, he is one of the men who tells her to escape to safety. She doesn’t listen.
Le Bret brings the bad tidings to Cyrano that Christian has been shot and mortally wounded—just as Cyrano is about to confess the truth to Roxane.
Fifteen years later at the convent, Le Bret brings news to Roxane that Cyrano is not doing well. He tells her he fears that solitude may be Cyrano’s undoing.
Roxane does not believe him, but de Guiche has plenty to say to Le Bret. When Roxane is out of hearing, he warns Le Bret to keep Cyrano at home as much as possible or he may suffer an "accident." Le Bret answers "coldly," so he may recognize this as a death threat.
Ragueneau arrives and discloses to Le Bret that Cyrano has suffered an accident, has a head injury, and is now unconscious. They two men hurry off to see their friend.
But he and Ragueneau come up empty-handed; Cyrano has left his sickbed to see Roxane.
The two men eventually come back to find Cyrano faring poorly as he talks to the oblivious Roxane.
They try to cheer him up by talking about frivolous things, like Molière stealing his lines for a play.
As Cyrano fades, Le Bret protests that it is not fair for such a noble man, friend, and poet to die so unfairly.
He and Ragueneau support Cyrano when he falls into their arms and dies.