Patterns of Amber is based on The Chronicles of Amber, a series by Roger Zelazny. I've never read the books, but the song has had me curious for a long time. Now that I've found the wiki on the series, the song makes much more sense, but I'm not sure if I'd like the books. Sometimes the filk is better than the stories they were based on. The song focuses on Corwin of Amber, the main character of the first five books.