Who is John Burke, and how does Lizabeth describe him?

John Burke is Miss Lottie's son.

John Burke was what was known as queer-headed. Black and ageless, he sat rocking
day in and day out in a mindless stupor, lulled by the monotonous squeak-squawk of the chair. A battered hat atop his shaggy head shaded him from the sun. Usually John Burke was totally unaware of everything outside his quiet dream world.