Gregor wakes up at nightfall. He notices that his side and one of his legs still hurt from the morning. He finds milk and bread by the door, and hungrily attempts to eat them, but despite the fact that milk used to be his favorite drink he finds it distasteful.
His appetite, or lack thereof, recurs often in the text, showing a connection between his body and his emotional life. Here the aspect of Gregor's mind that is still human continues to associate these fresh foods as things he would like to eat, but his body rejects these foods as they don't appeal to an insect. But it isn't so simple to say that there is a strict split between mind/body here, as what seems appetizing is a function of both body and mind, or of body influencing mind.
Gregor notices that his father isn't reading to Grete, though it is a nighttime tradition. Gregor is concerned, but he thinks about how his family has been able to live in peace and quiet since he's been providing for them, and he's happy that he's been able to give them this comfortable lifestyle. His thoughts turn to concerns about whether "all the quiet, the comfort, the contentment were now to end in horror." He calms himself by crawling around his room. He hears his family going quietly to bed, then settles under the couch to rest. He barely sleeps, and plans to "help the family to bear the inconvenience he was bound to cause them in his present condition."
Unlike in the morning, when Gregor seemed confused or even distracted while he inadvertently terrorized his family, now Gregor shows some understanding about the horror (and possible financial difficulty) that his metamorphosis has caused, how it has upended his family's routine and future. But he deals with this very human thought process in a decidedly cockroach-like way—crawling around and going under the bed—showing his inability to change himself to fit a more human mold.
In the morning, Grete checks on Gregor, and is still shocked by his state. She notices the uneaten milk and bread and removes them, bringing instead rotting vegetables and other old food. She leaves, locking the door. Gregor ravenously eats the food, particularly enjoying the moldiest portions. When Grete returns to remove the leftovers, he hides under the couch so as not to disturb her.
Grete's attentiveness seems to nourish Gregor as much as the food. Where he once planned to pay for her schooling, now the only thing he can do for her is hide—but for once, his intentions match his outcomes, and Grete is not disturbed. Meanwhile, Gregor hungrily eats things that once would have disgusted him. His body's needs is changing his mind's perceptions.
Grete covertly feeds Gregor again in the afternoon, when their father, mother, and the servant girl won't notice. Gregor isn't sure why his family didn't ever bring a doctor in. His family members talk freely around him because they don't realize he can understand. He overhears their conversations in the dining room, including the cook's desperate request to quit her job. The family releases the cook, and Grete and her mother must cook instead.
Grete's kindness, and the special bond she shares with Gregor, stands out even more clearly now that we know she's hiding her actions from the rest of the family. Gregor's concerns about the doctor show his aversion to accepting his new condition, hint that he's feeling neglected, and suggest that he doesn't understand the shame his family feels about him—they don't bring in a doctor because they don't want anyone else to know. The cook, for instance, quits her job because she can't stand to be in the house around Gregor.
Gregor overhears his father explaining the family's financial position, which is fairly stable because of their thriftiness. Gregor ponders how, at first, the family greatly appreciated all of Gregor's hard work as a commercial traveler, and then how they got used to it. Gregor also recalls how he'd hoped to support Grete's future studies in violin at the Conservatorium. Gregor's father decides that he must go back to work, as old as he is. Gregor's mother seems too old and unhealthy, and Grete is only 17. Gregor feels "shame and grief" thinking about his family having to work.
Gregor's feeling of neglect strengthens as he thinks about the way his family came to take him for granted when he was still human. The story is always concerned with the limits of sympathy: before Gregor's transformation, the family quickly came to take him for granted and to depend on him without gratitude (much as their sympathy for his plight as an insect will slowly erode). Still, Gregor feels responsible for them, and the shame he feels at their having to go to work shows how his self-worth came from living up to that responsibility, to meeting the expectations of their dependence.
Gregor often has trouble sleeping, and his eyesight worsens, so he can barely make out anything outside the window. Grete is both attentive to his desires (leaving the chair by the window for him to sit), and abrupt and frantic when she cleans his room. Gregor wishes he could thank her for her work, but also feels upset about her behavior.
Gregor's body transforms into an insect over night, but his full metamorphosis doesn't happen in an instant, as his cockroach body and tendencies continue to develop. Grete's patience diminishes on a parallel path. One might say that Grete too undergoes a metamorphosis—Gregor from man to insect; Grete from sympathetic to weary and uncaring.
A month after Gregor's transformation, Grete enters to find Gregor on the chair instead of under the couch as usual, and gets so scared she leaves and doesn't come back for hours. Gregor knows he is "repulsive" and spends hours setting up a sheet to cover the couch so she won't see any of him.
Though Gregor is irritated about Grete's hastiness, he now understands it. He has internalized the shame and disgust his family feels for him and now feels it himself. His only ideas for coping are passive—but if he tried to communicate, his family might be too scared to understand.
Gregor's mother and father don't enter with Grete but they are curious about him. After two months, Gregor's mother wants to come in to see him. In the meantime Gregor has been amusing himself walking on the ceiling, and Grete has moved the furniture around so he has easier access. Gregor's mother enters the room to help Grete move a chest, but they are unable to do so. Gregor's mother says that moving all the furniture might suggest to Gregor that they never expect him to get better. With her words, Gregor realizes how close he'd come to forgetting his humanity.
Gregor's hope that the presence of furniture will hamper his crawling and help him retain his humanity echoes the story's larger concerns with the interaction between physical and mental. Just as Gregor's body has influenced his mental state, he hopes his furniture will influence him in the opposite direction. Gregor's mother seems to understand this.
Grete disagrees with Gregor's mother and they work to remove the chest. Gregor feels agitated by all the movement in his room, and sad that they're removing his possessions, including the desk he'd used since he was a child. While Grete and his mother are out of the room, Gregor runs out from under the couch and scuttles onto the print of the lady with the muff to protect it from being removed.
Grete's reaction to her mother's plan shows that Grete cares more about being the one responsible for Gregor than actually considering what he might want. There is a sense in which Grete likes being the one upon whom Gregor is dependent (just as Gregor's self-conception when he was human was built around his family being dependent on him) , and puts her feelings about that before his own.
Grete returns, sees Gregor on the wall, and attempts to get their mother from the room without her noticing. However, Gregor's mother looks up, screams, and faints. Grete runs out to look for some smelling salts, and Gregor unsticks himself from the print and runs after her, hoping to help somehow. Grete is terrified to see him, drops some bottles, then runs back to his room, closing the door behind her so he can't enter. In desperation, Gregor climbs all over the ceiling and walls until he dizzily falls onto the table.
Gregor has again underestimated the horror his shape causes—which means he's also underestimated the bravery and care that his mother showed by trying to help him. This scene vividly shows how trapped he is in his own body—even when he tries nonverbal communication, he only causes panic, and his own panicked reaction to the panic he causes in others is an insect-like skittering.
Gregor's father returns. Grete calls from Gregor's bedroom that Gregor has escaped, and Gregor's father responds that he expected such a thing all along. Gregor thinks that his father is assuming that Gregor committed some violent act, so Gregor goes to sit outside his bedroom door to demonstrate his good intentions.
Though Gregor's father may seem villainous, as always in the story, no one is entirely good or evil. The father can't imagine that the cockroach is in fact his son, and on some level, he's right.
Gregor's father, however, is "not in the mood to perceive such fine distinctions," and excitedly yells at Gregor. Gregor notices that his father looks livelier and younger than before he took his new job, and is well-dressed in his bank attendant's uniform. Gregor's father seems to want to stomp on Gregor, and Gregor flees from him, though neither of them seems quite sure if it's really a chase.
Yet his father's perceptions of Gregor are so based on his disgust at how Gregor looks that he can't even begin to empathize with Gregor or recognize Gregor's nonverbal cues. Even in this moment of hysteria, Gregor notes how his family is coping well without him—which is both a positive development and a blow to Gregor's self-esteem, since Gregor cared so much about being the one responsible for the family.
As Gregor gets tired of running, Gregor's father begins to throw apples at him. One apple hits Gregor's back and gets embedded, causing Gregor massive pain. Gregor notices, as he passes out, his mother running out of his room, half-undressed because of her fainting fit earlier, and begging Gregor's father not to kill Gregor. Gregor faints.
Why is the father so aggressive? The answer must relate both to the father's preconceptions about cockroaches, and to his misinterpretation of Gregor's actions. Certainly no one in the family has tried their hardest to keep an open mind, though Gregor's mother does still see Gregor as her son. All of Gregor's family eventually follow in his father's path, coming to see Gregor based on his appearance, as an insect who could no longer possibly have anything Gregor-like about him. His father just moves down the path faster.