The theme of guilt could also be present. For example, if someone in the story was responsible for Muriel's death, they might be haunted by her ghost, and the story could explore the guilt that person feels.
One possible theme could be revenge. If Muriel was wronged in some way during her life, her ghost might be seeking revenge in the story.
Since I don't know the exact 'Muriel's Ghost Story', I can only assume some common aspects. Ghost stories often involve unexplained phenomena such as strange noises, cold spots, or objects moving on their own. In Muriel's story, perhaps there is a character who is haunted by Muriel's ghost. The story might start with this character noticing odd things around them, like a feeling of being watched. Then, as the story progresses, they might discover the reason behind Muriel's presence as a ghost, which could be related to an event that happened in the past, like a murder or a broken promise.
One possible theme could be mystery. Since there is a ghost involved, there would be a sense of the unknown and the fishboy trying to solve the mystery of the ghost. Another theme could be connection. Maybe the fishboy discovers a connection between the ghost, himself and the fish or the water.
Another theme could be fear. Ghost stories are often about creating fear, and in '222 the ghost story', the unknown elements related to '222' might be used to instill fear in the readers or listeners. For example, if the ghost always haunts at 2:22, that specific time can be a source of fear. Also, the presence of the ghost in the story would naturally bring a sense of dread and unease.
Muriel Spark's ghost stories often explore deep psychological themes. The ghosts can be seen as manifestations of the characters' inner turmoil. Instead of just focusing on scaring the readers with traditional horror tropes, she delves into the human psyche, making her ghost stories more thought - provoking than many others in the genre.
One possible theme could be loss. The ghost could symbolize something that has been lost, like a person, a relationship, or a part of oneself.
One possible theme could be displacement. The idea of being uprooted from one's home and becoming a refugee, like a ghost floating without a place to belong.
One possible theme could be the transition from a life of military combat to a pursuit of the supernatural. Another theme might be the exploration of the unknown, as the soldier leaves behind the familiar world of the military to face the mysteries of ghosts.
One possible theme could be the fear of the unknown. Since it's a ghost story, the mystery surrounding the ghosts and their existence can create a sense of unease.
One possible theme could be isolation. If the boy is a ghost or has ghost - like qualities, he might be isolated from the normal world.
One possible theme could be revenge. If the ghost in the story is that of someone who was wronged, they might be seeking revenge on those who caused their misfortune.