(Contains graphic sexual description in paragraphs 18 and 19 which may offend some readers)
By Teresa Larraz Mora
MADRID, July 20 (Reuters) - George R.R. Martin, author of the unfinished epic fantasy saga "A Song of Ice and Fire" rejects inevitable comparisons with J.R.R. Tolkien, whom he loves, but his novels are enjoying similar mainstream success in the usually niche genre.
His seven-tome series, of which he is currently working on the sixth instalment, has sold more than 15 million copies worldwide, while the HBO series based on the novels, "Game of Thrones", has won massive audiences.
The usual fantasy mix of kings and dragons is interwoven with tales of sex and incest, violent power struggles and intrigue and is based in a land of ancient interfamily feuds where no character is safe from sudden death.
Martin, 63, who has had a long career as a science fiction writer and a frustrating 10 years as an under-appreciated Hollywood screenwriter, says he loves to write complex characters and keep his audience guessing.
"One of the things I love, and I'm a voracious reader as well as a writer, is books that surprise me, that are not predictable," Martin told Reuters in a telephone interview.
"Nothing bores me more than books where you read two pages and you know exactly how it's going to come out. I want twists and turns that surprise me, characters that have a difficult time and that I don't know if they're going to live or die."
On his third visit to Spain, Martin travelled to Aviles, Madrid and Barcelona where he met his Spanish fans, to whom he made a special dedication in his fifth and latest novel of the series "Dance with Dragons".
Inspired by historical dynastic wars, such as England's Wars of the Roses, the plot is set in a fictional, medieval world, where kings and queens and knights and dragons are entrenched in the battle for power of the Iron Throne in a tale filled with treachery, love and lust.
"I like grey characters, fantasy for too long has been focused on very stereotypical heroes and villains," Martin said.
"And when I look around, I don't see pure white shining heroes and absolutely black villains, I see a lot of flawed human beings who have it in them to be heroes or villains; it's a matter of the choices that they make in crucial periods in their lives, in moments of stress and emotional turmoil."
After the last two books took over five years each to be published, it may yet be a while before avid fans worldwide can get hold of "The Winds of Winter", the sixth volume, although they can get a taste of one of its opening chapters on his website.
The wait will be shorter for the third season of HBO's "Game of Thrones", due March 2013.
Martin, who refused to cut the story radically short to make a film, accepted an offer from HBO producers David Benioff and Dan Weiss to make a TV series, with a season dedicated to each book.
POWER, SEX AND VIOLENCE
Martin's books, which also drew on the events of the 100 Years War in the 14th and 15th centuries, the Crusades and the Dark Ages for inspiration, deals with the complicated web of intrigue that comes with fights for power.
"One of the characters poses a riddle: there's a king and a rich man and a priest, and a common sellsword (mercenary). Each of the three men tells the sellsword to kill the other two. Who lives? Who dies? Who has the power in that situation? Where does power derive from?"
"Power is a powerful force and very seductive," he added, but when asked, smiling, he said it was not "any specific allegory to the current economic crisis."
Martin, who has a blue collar background in an industrial suburb of New Jersey said he has been surprised with the reaction against explicit sex scenes coming from some American readers.
"I can describe an axe entering a human skull in great explicit detail and no one will blink twice at it. I provide a similar description, just as detailed, of a penis entering a vagina, and I get letters about it and people swearing off," he said.
"To my mind this is kind of frustrating, it's madness. Ultimately, in the history of world, penises entering vaginas have given a lot of people a lot of pleasure; axes entering skulls, well, not so much."
Martin also dismissed internet speculation about his health as offensive and said he will never retire.
"I have many books that I want to write, I'd like to think that I'll be around for another 20 years or so and write another dozen novels, probably some sort of imaginative literature ... Never again another seven volume saga." (Editing by Paul Day and Paul Casciato)