Musician Nathaniel Ayers, left, and Los Angeles Times columnist Steve Lopez have maintained and deepened their friendship, which became the subject of a book by Lopez and a movie, "The Soloist."Los Angeles Times columnist Steve Lopez had no idea what was in store for him when he first spoke to Nathaniel Ayers that day in the park 4 1/2 years ago. As the journalist puts it now, "it was a serendipitous encounter that changed the lives of two people from different walks of life." Dressed in tatters and standing beside a shopping cart heaped with all his possessions, Ayers was obviously homeless.