IT WAS AN invitation no book reviewer could refuse. Several weeks ago, well in advance of the pre-Christmas turmoil, I and a dozen other regular reviewers of fiction for Book World received an invitation to participate in a holiday symposium on this tantalizing question: "Which character in fiction would you most like to be, and why?"

Not in the least surprisingly, none of those offered the chance to participate in this novel seminar declined to do so. For some, as you can see from the pieces below, the choice was easy; for others it was difficult, torn as they were among a number of characters who had managed to work their way into their hearts.

SO MANY of the noblest characters come to unhappy ends, and even the great wish-fulfillment figures, like Cinderella or the Count of Monte Cristo or Black Beauty, suffer unduly before they start to have fun. Mature responsible adults, like Tolstoi's Levin, have such a dull time of it in fiction that I would rather wish myself to be Svengali or Lovelace or Heathcliff. Kingship seems a happy medium, however, and so I'll assume the crown of Mary Renault's Theseus in The King Must Die, thereby enjoying a tour of pre-classical Greece and of Crete in the days of its glory as well as a career as a popular bull-dancer. Renault notes: "It is not inconceivable that a leading torero, enjoying perhaps the combined prestige of a Manoleto and a Nijinsky, might become a princess's lover, and play some part in the downfall of the regime." By comparison, Yourcenar's Hadrian is a stuffed toga, and Mann's Klaus Heinrich (in Royal Highness) a mere civil servant (though they'd be my second and third choices). Only after three reigns would I try for something more transcendental: Moby Dick: