Hooked: How to Build Habit-Forming Products - Нир Эяль

Best friends and sisters, the four Padavano girls bring loving chaos to their close-knit Italian American neighborhood. William Waters grew up in a house silenced by tragedy, where his parents could hardly bear to look at him, much less love him. So, when he meets the spirited and ambitious Julia Padavano, it's as if the world has lit up around him. 

With Julia comes her family: Sylvie, the family's dreamer, is happiest with her nose in a book; Cecelia is a free-spirited artist; and Emeline patiently takes care of them all. But when darkness from William's past begins to block the light of his future, it is Sylvie, not Julia, who becomes his closest confidante. The result is a catastrophic rift that leaves the family inhabiting two sides of a fault line.