I'm sorry, I haven't read this specific novel. It could be about the private and personal experiences of the sister character, perhaps her relationships, dreams, or secrets.
Another theme could be privacy itself. It may show how the sister tries to protect her private space and what happens when that privacy is invaded. It could also be about self - discovery. The sister may be on a journey to understand herself better in her private life, away from the outside world's expectations.
The novel might be interesting in terms of character development. As it's about the sister's private life, we could see her grow and change as she faces different situations in her private world. For example, her relationships with friends or romantic interests could shape her character in unique ways.
One characteristic could be its unique plot. It might blend the concept of an internet novel with real - life situations in an interesting way. For example, it could show how the protagonist's life starts to resemble the events and tropes often found in internet novels, leading to both comical and thought - provoking scenarios.