Indexes to fiction are sometimes made, although they are unusual. Philip Bradley considered the topic in his 1989 article for @theindexer.bsky.social www.liverpooluniversitypress.co.uk/doi/epdf/10....
Long works of literature need to have a special index at the back showing the page number when each character was introduced. Otherwise you're thumbing backwards trying to remember who this person is in this huge book you've been reading for weeks.