LitCharts assigns a color and icon to each theme in A Man Called Ove, which you can use to track the themes throughout the work.
Memory and Grief
Rules and Order
Love, Family, and Community
Principles, Fairness, and Loyalty
Summary
Analysis
When Ove leaves the hospital, the Saab is filled with people. Parvaneh gives Nasanin crayons, which makes Ove angry. Patrick is wedged into the middle of the backseat and tries not to disturb the newspaper Ove put down to keep his seats clean. Nasanin drops a crayon and Jimmy picks it up from his front seat. Jimmy's phone pings and Patrick asks who owns the cat. Parvaneh insists that it's Ove's, but Ove insists that the cat's a vagrant. However, Ove gets very angry when Patrick suggests they hand the cat in to a shelter.
Ove's reaction to Patrick's suggestion shows that whatever Ove might say, he does believe one hundred percent in people (and cats) remaining in their communities and with their families. This suggests that if Ove turns out to be wrong about the white shirts and Rune, he'll still fight to keep Rune in his home on principle.
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Jimmy asks if they can stop to get something to eat. Ove thinks about swerving off the road but realizes that all these people might then join him in the afterlife. He slows down and Parvaneh says that she and Nasanin need the restroom. Jimmy suggests they stop at McDonald's, and when Parvaneh glares at Ove, he agrees to stop. Ove doesn't go into the restaurant.
Again, Ove uses what Sonja might think were he to turn up in the afterlife in his current state as a way to steer himself towards doing the right thing. Her memory, along with Parvaneh's insistence that he not be rude, guide his behavior and steer it towards better behavior.
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Ten minutes later, Parvaneh comes out of McDonald's and gets in the passenger seat. She asks Ove for help passing her driving test. Ove thinks it's a joke, but Parvaneh explains that Patrick won't be able to drive for months because of the casts. Ove is confused, and Parvaneh patiently explains that she doesn't have a driver's license. She asks Ove if he really wants someone else to teach her to drive and gets out of the car.
Parvaneh uses Ove's love of rules, and his belief that his rules are the only rules worth following, to convince him to teach her to drive. Ove's confusion stems from his belief that "real" people do things, like drive. This suggests that he views Parvaneh as a competent and valuable person, despite their squabbles.
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Jimmy appears at the passenger window and asks Ove if he can eat in the car. Ove puts down more newspaper and tells Jimmy to make his phone stop making noise. Jimmy says that work keeps emailing him and explains that he programs iPhone apps. Ove stops by the bicycle shed and his passengers get out of the Saab. When Parvaneh lifts out Nasanin, Nasanin waves paper and yells. Parvaneh gives Ove the piece of paper and explains that Nasanin drew a picture of Ove. Ove is unimpressed, but Parvaneh points out that the figures are all drawn in black except for Ove, who is drawn in bright colors. She tells Ove that Nasanin always draws Ove in color because she thinks he's funny.
Jimmy effectively meets Ove halfway in regards to rules when he asks permission to eat in the car. Ove's community is beginning to listen to each other and truly respect each other. Nasanin's color drawing of Ove points back to the narrator's assertion that Sonja was Ove's color. This drawing suggests that Ove is finally finding some color in his life after Sonja's death, and that it's coming from his immersion in a new community.
Ove puts the Saab in the garage and considers trying to kill himself with the exhaust again. He thinks he misses Sonja, but he looks at the cat asleep on the passenger seat and turns the car off. After Ove gets up the next morning and makes his inspection, he shovels his walkway and then his neighbors' walkways.
Ove's ruminations on suicide are getting less intense and less action-based. The cat continues to act as a reason to stay and as a vehicle for Sonja's morality and kindness. When Ove starts giving back to the community, we see that he's truly choosing to become a part of it.