Critic Alfred Kazin believes Joe Christmas to be the most solitary character in American fiction. Would the villian of " A Good Man is Hard to find" by "Flannery O'Connor" or the heroin of "The Yellow Wallpaper" by " Charlotte Perkins Gilman" rival Joe's isolation?
While founded on experienced analysis, critics express their own opinions about literature and literary characters. If you agree with Kazin, then it might be hard to find a rival for the solitary experience of Christmas. If you disagree, then the heroine of Perkins "The Yellow Wallpaper" might be a rival for the award of "most solitary" character.
The reason Christmas may seem the most solitary is perhaps not his life as constructed by Faulkner, but Faulkner's modernist style that embodies defragmentation and solitary psychological angst: the author may be more solitary than the character.