The theme of the necessity of pain plays a significant role in the final section as well. In his letter to Van Houten, Augustus writes about the marks he says we all want to leave on the world, and they’re generally the things people do to prove they’re important in some way. It’s notable that he refers to these marks as “scars.” The term implies that a wound, and therefore pain, has been inflicted. While Augustus seems to think most of these scars are harmful, particularly those we inflict as a result of our own vanity, he makes it clear that not all are. The scar he left on Hazel is in this latter category. It’s proof that he mattered to her, that she loved him, and he’s happy he caused it. The type of pain that inflicts this scar is unique in Augustus’s mind. He says we can’t choose whether or not we get hurt, but we can choose who hurts us. In other words, we have no control over the pain we suffer, except in this one instance where we do control who inflicts pain on us. Those people, he suggests, are the people we love. His metaphor creates a direct link between pain and love.

Throughout the novel, Augustus has questioned the meaning and purpose of his life without any clear answers, but here he finally seems to draw a conclusion about what makes a life significant. Augustus’s main fear through most of the novel has been dying without having accomplished something meaningful, and he has always equated a meaningful life (and death) with doing something heroic that people will remember him by. That glory and fame, he thought, would be proof that he mattered. But in the letter to Van Houten that Hazel reads, Augustus appears to find a slightly different measure for proving he mattered and that his life had meaning. He refers to the marks we want to leave on the world to prove we’re significant as “scars,” and while Augustus seems to think most of the scars people leave, like mini-malls, are the wrong kind, he is happy about the scar he left on Hazel. He suggests that, because it resulted from their love for each other, it means he genuinely mattered, at least to her. It also satisfies his desire to be remembered after his death, as he knows Hazel will carry “his scar” with her always.

Hazel, meanwhile, comes to her own conclusions about her meaning and purpose in life. When Patrick asks her in Support Group why she doesn’t die, she actually stops to consider the question rather than just give her stock answer, which was that she went on living for her parents. But on thinking about it, Hazel, taking influence from what her father said about the universe wanting to be noticed, thinks that she wants to go on living in order to observe the universe. (The thought also recalls Augustus’s comment in his letter to Van Houten that the real heroes in the world are the people who notice things.) This change in her thinking seems to be the result of her relationship with Augustus. At the start of the novel, she didn’t seem to think much mattered, and her focus was primarily to avoid causing anymore suffering in the world. Now, however, she feels she owes a “debt” to all those who aren’t living, and the term indicates that she feels she has something of great value that they don’t: namely, life. What’s significant about this thought is that the Hazel we see at the start of the novel didn’t seem to think much of life’s value. She only came to see this value after Augustus greatly enriched her life, and sees her purpose as continuing on with her life, not to do anything extraordinary necessarily, but simply to use that life to notice what’s around her. Living, her thinking suggests, is its own purpose.

The dream Hazel briefly mentions about finding herself “boatless in a huge lake” ties into the water symbolism running throughout the novel, and its timing suggests a connection to Augustus’s death. Hazel has previously used drowning as a way to describe how she feels in particularly awful situations, like when she had to be hospitalized because of her lungs and after Augustus died. Here the threat she faces in being without a boat is again that she’ll drown. Moreover, water has been used as a symbol to represent pain, both psychic and physical. Augustus was Hazel’s refuge from this pain, but now she finds herself without him. Viewing the dream with this symbolism in mind, Hazel finds herself in danger of being overtaken by the pain she’s experiencing now that she’s lost Augustus, who is represented by the boat that Hazel finds herself without.

The final words of the novel, Hazel’s “I do,” are significant in a few ways. For a start, they mark the first and only instance of Hazel using the present tense during her narration the novel. This change in tense is notable because it indicates that Hazel currently loves Augustus. Her love hasn’t come and gone but persists in the present. The words are also a prominent feature of wedding vows, which are, in theory at least, supposed to bind two people together forever. Using those words suggests Hazel is entering into an agreement with Augustus to continue loving him into the future, and both meanings indicate that Hazel doesn’t see Augustus’s death as an end to their love for one another. The idea ties into the fear Hazel talks about with her mother, whom Hazel once overheard lamenting that she wouldn’t be a mother anymore after Hazel died. Through these scenarios, the novel suggests our relationships don’t end with death. Just as Hazel’s mother reassures her that she’ll still be her mother even after Hazel dies, Hazel acknowledges with her words that her relationship with Augustus will continue despite his passing.