Note: this response contains spoilers.
Everything, Everything is the debut novel of Jamaican-born author Nicola Yoon. The book's subject matter is so poignant that it was made into a film in the following year. The protagonist, Maddy, is diagnosed with severe combined immunodeficiency (SCID). She lives a simple and restricted life with her mother and nurse. Her health must be tracked diligently, and she cannot go outside. One day, she catches the eye of a boy, Olly, who is moving in next door. Maddy and Olly meet, with the aid of Maddy's nurse, and they continue to message one another online. Olly convinces Maddy to go to Hawaii with him, as she tells him she will be able to endure the trip.
When a doctor in Hawaii has to treat Maddy, who becomes seriously ill while there, it is revealed that Maddy does not in fact have SCID—her mother wanted her to be kept safe from the outside world after losing her husband and son (Maddy's father and brother).
Emotions run high throughout the book. First, there is the debilitating grief suffered by Maddy's mother (which becomes clear at the novel's end). Next, there is abuse, suffered by Olly at the hands of an abusive father. Finally, there is the charming young love between Olly and Maddy, rendered all the more genuine in its portrayal because of Maddy's illness and limited experiences.