In Kafka's The Metamorphosis, we are able to understand the life Gregor had before he was transformed into a giant insect.
The first hint we get of what Gregor's life was like when he was working is found at the very beginning of the story. As he struggles—with his new "body"—to get out of bed, Gregor grumbles a great deal about how hard his job is on him, and that this must be affecting his present health:
“Oh God,” he thought, “what a strenuous occupation I've chosen! Always on the road, day out, day in. The rigors of the job are much greater than if I were working locally, and, furthermore, the nuisances of traveling are always imposed upon me—the worries about train connections, bad meals at irregular intervals, fleeting human contact that is ever-changing, never lasting, and never expected to be genuine.
We receive several hints throughout the story as to how life at home was for Gregor. The following quote not only shows how much work Gregor has had to do, but also how he fills his hours with his family at night. Gregor's mother reports:
The boy has nothing in his head except business. I'm almost angry that he never goes out at night; right now he's been in the city eight days, but he's been at home every evening. He sits here with us at the table and quietly reads the newspaper or studies his travel schedules.
After Gregor's transformation, the family looks at their financial prospects. For many years Gregor has been a bulwark of security for this parents and his sister, working constantly to support them after a financial disaster is father suffered.
Gregor's only concern had been to do everything in his power to allow his family to forget, as quickly as possible, the bad business luck that had brought them to complete despair. And since that time, he had begun to work with a particular fervor, going almost overnight from being a minor clerk to a traveling salesman, who naturally had a lot of other possibilities for earning money because his success at work was transformed immediately into the form of a cash commission that could be laid on the table at home before his astonished and delighted family.
The family has existed comfortably while Gregor has been working himself to death to support the lifestyle the rest of his family enjoys. The family's feelings toward Gregor, and his response to their behavior, is described starting from when he first starts to bring home his wages. We also learn that he is very close to his sister:
Those had been fine times, and they had never thereafter been repeated—at least not with the same splendor—despite the fact that Gregor later earned so much money that he was capable of bearing the expenses of the entire family, as he also did... they accepted the money gratefully, and he gladly handed it over, but it no longer resulted in that special warmth. Only the sister still remained close to Gregor...
For a long time before his "change," Gregor had planned to send his Grete to a music school. When she plays the violin for the tenants, we can infer how important her music always was to Gregor:
...his sister was playing so beautifully. Her face was turned to the side, and her gaze, scrutinizing and full of sadness, followed the lines of notes...Was he an animal, that music would so move him? ...He was determined to get as far as the sister...and thereby to express that as nobody here thought that her playing was worth their time...([he] thought it was worthwhile).