Lidewij Vliegenthart also appears in the novel The Fault in Our Stars by John Green. She is Van Houten's personal assistant and is writing a doctoral thesis in American Literature. She invites Hazel and Augustus to Amsterdam. She is outraged by Van Houten's behavior and immediately quits her job with him when she notices how badly he treats Augustus and Hazel.
After the terrible encounter, Lidewij runs after the teenagers and apologizes to them. She drives with them to the Anne Frank Museum to save the day. Later, Lidewij also plays an important role. She helps Hazel find the last written thoughts of Augustus as he writes to Van Houten before his death and asks him for help.
Monica is Isaac's girlfriend at the beginning of the novel. She has brown hair is tall and, according to Hazel's description, curvy (Chapter 1, 89%). Hazel and Augustus observe the two as they kiss outside the church after the support group:...