The relationships in the Samsa household are defined by tension and resentment. Before his metamorphosis, Gregor is the only working family member. His job as a salesman supports the family financially, and Gregor takes his role seriously. He often sacrifices so his family can be comfortable, although he does sometimes feel slighted (meaning he doesn't think his family appreciates him enough).
Gregor's father has failed to support his family himself, so he behaves aggressively toward his son, due to his feelings of inadequacy. Gregor's mother tries to defend him on occasion, but she gives in to her husband's anger. Gregor's sister seems to be the family member for whom Gregor holds the most affection. Before he changes, he expresses the desire to pay for her musical training.
Unfortunately, after his transformation, every memer of the Samsa family abandons Gregor, wanting him to simply disappear. They are disgusted by his appearance, and there is a sense that they somehow feel betrayed by his misfortune. In the end, he sacrifices himself once again for their needs.
In Franz Kafka's The Metamorphosis, Gregor Samsa is a main character who loves and cares for his family, simply because it is his place to do so. When Gregor's father loses his job, Gregor takes over as the breadwinner for his household, and never resents his father or questions the fairness of his situation, because as a loving son, this is his duty. He attempts to continue in this responsibility even after he discovers he has been transformed into an insect.
Gregor is close with his sister Grete, and she is the one who becomes his caretaker after his transformation. If this strange change had happened to her, rather than to Gregor, he would have done the same for her, as any close family member would.
Gregor does not, however, have an ideal relationship with his father. His father, whom he rarely refers to by name, is distant and seems unkind. He has failed to provide for his family and shows no sympathy for Gregor after the metamorphosis, instead becoming violent toward his son in several instances. It may be said that in his behavior toward the "intruder," Gregor's father is once again becoming the patriarch of the family, rescuing his innocent wife and daughter from a hideous creature.
By the end of the novel, Gregor is no longer the provider for his family, and consequently, each of the other family members have assumed their "correct places" in the familial hierarchy, despite disregarding Gregor himself in the process.