A man who couldn't die surrounded by books and memories

What is my purpose for being immortal and am I the only one? These questions plague the main character who is in search of answers. His job owning a used bookstore seems perfect as does his choice of surrounding himself with books as his only friends. When he sees someone whose inability to die seems oddly like his own, his interest is piqued. I love that the language and easygoing opening to this reads like a book about a quiet discovery of immortality and purpose and less like a fantasy thriller. Someone with decades of knowledge and memories has to be a character you want to get to know more about.