Both are beautiful black and while films by director Lee Joon Ik focused on the lives of writers that paint an insightful picture of some aspect of the period they are set in. They are slow-paced, poetic, and create a sort of intellectual or emotional portrait of the historical figure on whose life they are based. They also focus on these writers' important relationships with the other leads, who function as foils and as major characters in their own right.
Both of these films are rather slow-paced and have significant ideological conflicts at their centers. The clash of ideologies in The Fortress manifests as a political debate while the king and his ministers try to make decisions during a siege. The Book of Fish explores the value of different types of knowledge and learning by following the relationship between the two leads, who come from very different backgrounds, thus have different beliefs and mastery of different skills. Both are excellent historical films with great performances and beautiful cinematography. Though both have their uplifting and depressing moments, the Book of Fish has an overall more light-hearted tone, while The Fortress is more serious and bleak.
