irony
Irony within The Fault in Our Stars is pretty big. The hugest irony in the book would be that Hazel was nervous about starting a relationship with Augustus because she knew she would die within years and she didn't want to hurt him by her dying, and when she finally did start a relationship with him, he turned out to be dying faster than her. She didn't want to hurt him by dying and he ended up hurting her by his death.