There are some multi-chapter AUs that span whole seasons, like the Lustra Verse (http://lustraverse.livejournal.com/511.html) and fanspired's The Song Remains the Same Verse (http://fanspired.livejournal.com/1394.html), also Diana_Lucifera& tersichore's Brother's Blood, Father's Gun (http://diana-lucifera.livejournal.com) series. Not quite what you asked for but maybe it will interest you since I've never seen any novelizations like that online.