Here's the template, put in the Subtitle field:
Code:
program:
if field('#fanficcat') then
template("{#fanficcat:'sublist(list_sort($, 0, ','), 0,1,',')'} | {#fanficstatus}")
fi
It returns no value for books that don't have a populated #fanficcat, but for some reason it does not get rid of other subtitles.