Publishers and critics alike have found difficulty in classifying Joyce's writing. His novels have been categorized as fantasy, science fiction, horror, and mainstream literature—with some even overlapping genres. Joyce utilizes a wide variety of settings and character perspectives. Settings include Scotland, The English Midlands, Greece, the Middle East, and the jungles of Thailand. He has penned for both adult and juvenile protagonists, with an emphasis on strong female characters. The greater unity in Joyce's works, however, lies in their thematic and philosophical topics. Bill Sheehan, who wrote the introduction for "Partial Eclipse", states: