The First Fifteen Lives of Harry August by Claire North
No matter what he does or the decisions he makes, when death comes, Harry always returns to where he began, a child with all the knowledge of a life he has already lived a dozen times before. Nothing ever changes.
As Harry nears the end of his eleventh life, a little girl appears at his bedside. ‘I nearly missed you, Doctor August,’ she says. ‘I need to send a message.’
This is the story of what Harry does next, and what he did before, and how he tries to save a past he cannot change and a future he cannot allow.