As Aziraphale and Crowley begin to settle down in their new life apart from Heaven and Hell, Aziraphale begins to get restless. When Aziraphale encounters a strange youth on the doorstep of A. Z. Fell and Co., he allows curiosity to get the better of him and welcomes them in. After learning of their desperate situation, he easily finds compassion for them and offers them a place to stay. After all, he always found humans quite intriguing. And surely he won't get too attached, right? (Set about a year after season 2. Entire backstory is explained throughout the book. Sorry guys I'm American.)