This scene is set in the street outside Gretchen’s house. Her brother Valentine, a soldier, enters. He recalls how his comrades used to get drunk and toast to pretty girls, while as he sat relaxed, unconcerned by their bragging talk, until he would ask if there was any girl who could compare with his own sister. The men would all agree that Gretchen was the flower of her sex. Now, however, Valentine fears that his sister’s honor has been compromised, and it maddens him to think how she’ll be talked about.
By this point in the play, news of Margarete’s sex out of wedlock has spread around town, bringing shame on her and her family. It’s also quite likely that Margarete’s mother is dead by this point, poisoned by the sleeping potion Margarete gave her. Valentine is deeply invested in social and religious conventions.
Faust and Mephistopheles enter, and Valentine swears that if his sister’s lover is one of these two, then that man won’t escape alive. Faust is tranquilly ecstatic, while the devil is energetic, for Walpurgis Night is approaching. Faust wishes he had a gift for Margarete, but Mephistopheles tells him not to worry about it. The devil then sings a song (accompanying himself on a guitar he happens to have) about a woman named Kate, who loses her virginity to a rogue.
The cerebral Faust is ecstatic to see Margarete again, and oblivious to how he’s played a part in bringing her to disgrace. The devil already knows about Margarete’s fall, and is surely relishing her suffering. Mephistopheles’ song about Kate parallels Margarete’s story, and the devil sings it with the sadistic purpose of enraging Valentine.
Valentine advances on Faust and Mephistopheles, cursing the devil’s song and breaking his guitar. He says it’s time to break some heads. The devil urges Faust to duel Valentine. Faust does so, drawing a sword he carries on his person; he is magically aided in parrying the soldier’s thrusts. Valentine feels his hand becoming numb, presumably as a result of magic, and the devil orders Faust to strike Valentine. Faust stabs him and Valentine falls in pain, mortally wounded. Cries of blood and murder are heard, and Faust and Mephistopheles escape into the night.
Mephistopheles is like the playwright and theater director here, coordinating a duel and then scripting the fates of the duelists with malicious glee. Faust has no good reason to fight Valentine. He doesn’t even know who he is, it seems, and so we can only assume that Faust fights him because of the devil’s bad influence. He came to see Margarete, but instead he’s now killed her brother.
Martha, Gretchen, and some townspeople pour into the street, bringing light, and they discover that a brawl has taken place: the murderers have fled, and Valentine lies dying. Gretchen mourns for her brother, but he tells her in front of all the townspeople that since she is a whore now she should make that her occupation. Gretchen is appalled. Valentine says that he knows of her secret lover, claims that soon she will have many more, and foresees the time when all the townspeople will avoid her for being a slut as they would avoid an infection-breeding corpse. She’ll be damned as long as she’s on earth, he says.
With misogyny and cruelty, Valentine condemns his sister’s behavior in the most unforgiving terms. Her life, he predicts, will become a living hell. He shortsightedly sees the world only through the lens of human society and convention, without recognizing the divine scheme of things—the whole of which humanity is just a part. Gretchen must be deeply shaken by her brother’s cruelty, which in part motivates her to kill her infant.
Martha tells Valentine to commend his soul to God in his dying hour, not to slander his sister. Valentine says that if only he could lay hands on the scrawny vile body of his sister and kill her, he’d hope to get abundant pardon for his sins. He demands that Gretchen not shed tears. He tells her that she gave his heart the fatal blow. Valentine dies.
Martha is right to remind Valentine that human society isn’t everything, especially when one is about to leave it for the afterlife. But Valentine draws all of his life’s meaning from what happens on earth, hence his disturbed and disturbing last words.