Hazel's childhood memories
Several flashbacks in the novel The Fault in Our Stars by John Green describe situations from the main character’s childhood. A few examples are given here, where Hazel feels a longing for the past.
The swing that her father set up for her as a child reminds the first-person narrator that she was healthy once:
It’s not like I had some utterly poignant, well-lit memory of a healthy father pushing a healthy child and the child saying higher higher higher or some other metaphorically resonant moment. The swing set was just sitting there, abandoned, the two little swings hanging still and sad from a grayed plank of wood, the outline of the seats like a kid’s drawing of a smile (Chapter 8, 57%).
The swing symbolizes of the time when Hazel was not ill.
There is a similar scene when the characters are at the airport about to board the plane to Amsterdam. When Hazel has to go through the security scanner without her oxygen machine, she remembers the feeling of being healthy. A memory from her childhood comes to mind, because this is the only time she has ever been healthy:
Walking through the X-ray machine marked the first time I’d taken a step without oxygen in some months, and it felt pretty amazing to walk unencumbered like that, stepping across the Rubicon, the machine’s silence acknowledging...