In many ghost stories, there is often a skeptic character who doesn't believe in ghosts at first. There could be such a character in 'the lawrence arms ghost stories'. And then there might be an old-timer in the story, someone who has knowledge about the local hauntings or the history behind the ghosts. There could also be a victim of the ghostly activities, someone who is being haunted in a more direct way.
Well, without having read it precisely, we can assume there would be a central character. This character might be a young person, perhaps a teenager or a young adult, who is new to the area where the ghost stories are set. There could also be a local guide - like an old man or woman who has lived in the area for a long time and knows all the spooky tales. And then there might be the ghosts themselves, which could be considered characters in a way, with their own backstories and motives for haunting.