A key element of the Southern Gothic tale (unlike the traditional Gothic story) is that it reveals the horrific or grotesque through traditional Southern American issues such as slavery and racial bias. Rather than dark and remote settings, atmosphere containing mostly bad weather, or the presence of the super-natural as a demonic element, the Southern Gothic reveals the "horrific" or "grotesque" situations of America's history. This is done through characters who possess blatant bigotry and egotistical self-righteousness.
Scout, as the narrator of To Kill A Mockingbird, is presented as young and innocent, but by no means ignorant. In fact, she is expected to be ignorant because she is young, but do not forget the narrator is the adult Scout, looking back. In this way, the young Scout is privy to several key pieces of information (especially character and situational nuances) which the adult Scout presents without bias. In this way, Harper Lee manages to reveal several instances of social prejudice and injustice without sounding preachy nor tolerant. This balance is created through Scout's childlike honesty and ability to tell things as she remembers them. It often comes across as both humorous and pitiful.