Before meeting Ove, Sonja had only ever truly loved three things: her father, books, and cats. She'd had suitors, but none of them looked at her like Ove did. Her friends told her that Ove was Ove and would always be grumpy, but she loved his belief in justice and hard work. She understood that men like him didn't exist much anymore, and she loved making him smile. Sonja taught hundreds of troubled students how to read Shakespeare over her nearly 40 years of marriage to Ove, but Ove refused to read any Shakespeare. He did make her beautiful bookcases for all her books, however.
Sonja recognizes that even when he’s young, Ove exists in a time period that's a mere memory. This explains Ove's unwillingness to modernize in the present: modernizing would entail even more work, as Ove would have even more time to bridge. The narrator describes exactly how Sonja gave back to her community through teaching: she taught troubled students and gave them purpose and success. Ove busied himself making things for Sonja, not joining her in her more intellectual interests.
Ove only met Sonja's father a handful of times. Her mother died in childbirth and he never remarried. He lived in the far north all alone except for Ernest, a massive farm cat. Sonja named him after Ernest Hemingway, who was one of her favorite authors. Ernest regularly went fishing with Sonja's father.
Sonja's father is a loner similar to the version of Ove we see in the present. His community consists only of his daughter and the cat—echoing Ove’s growing (if reluctant) attachment to the neighborhood cat and Parvaneh’s family in the present.
When Sonja brought Ove to meet her father for the first time, they sat silently for an hour while Sonja tried to make conversation. Sonja's father didn't like Ove because Ove was from the town and didn't like cats, while Ove felt he was at a job interview. Finally, Sonja angrily kicked Ove under the table, and he asked Sonja's father about his Scania truck. Ove mentioned that Saab is making Scania trucks now, and Sonja's father angrily said that Saab making the vehicles doesn't make them Saabs.
Despite Ove and Sonja's father's perceptions that they are two very different (and opposed) men, they share a deep loyalty to their car brand of choice. Both brands are also Swedish, which seems to make Ove view Sonja's father more favorably. Their mutual grumpiness and stubbornness can then even unite them.
The narrator explains that Sonja's father always drove Scania trucks and felt quite betrayed when Scania merged with Saab, while Ove had suddenly become very interested in Scania vehicles after the merger. Ove asked if the truck ran well and when Sonja's father said it didn't, Ove asked to look at it. The two men got up and went out to the truck. Sonja's father came back in and Sonja thanked him for accepting Ove. He asked Sonja if Ove fished and when she said no, he said that Ove would have to learn.
Cars allow Ove and Sonja's father to bond. Ove channels his father here as he works on the Scania's engine and in return, he gets a reasonable relationship with his partner's father. Sonja's father shows that he accepts Ove as a fixture when he asks if Ove fishes. It's implied that fishing is something that the two of them will share, regardless of Ove's thoughts at the time.