In "A Christmas Memory" "nostalgia fiction" by Truman Capote. He writes of the old woman:
We are each other's best friend. She calls me Buddy, in memory of a boy whos formerly her best friend. The other Buddy died in the 1880s, when she was still a child. She is still a child.
So, Buddy is the child Truman Capote. At the time of the story he is seven. To find he he looked like, you merely need to locate a biography of Capote on a search engine or in a bookstore or library. Capote was short, with a short neck and rather rounded face that had wide-set. thoughtful eyes, a short, straight nose. From his name and origin of birth (New Orleans), Capote was probably French. (Of course, Capote is characterized in Harper Lee's "To Kill a Mockingbird" in which Dill is described as rather chubby and unathletic.