He wrote Fionavar just after finishing the editing work on The Silmarillion with Tolkein (jr.). It isn’t hard to get a sense of the imprint all the Tolkein stuff had on him. Still good page turners, but they were the end of me and most fantasy tropes - as soon as I run into the wizened wizard, exiled prince, or (worst of all) yet another rehashing of the Arthur & Lancelot stories I put the book down.