I'm not sure who exactly Sebastian Quinn is in this context without more information. It could be a character in a movie, a book, or some other form of media that is based on a real - life story.
Well, we could expect to see the authenticity of real - life situations. Maybe it'll show how Sebastian Quinn interacted with the people around him, his family, friends, or colleagues. It might also reveal the social and cultural environment of the time when his story took place. If it's a good adaptation, it should give us a deep understanding of his character and the events that shaped his life.
The novel can go more in - depth. It has the luxury of time and space to really dig into Harley's thoughts and feelings, which is harder to do in a movie or a short - form TV show. For example, it can describe her internal struggles in great detail.