A letter written by ‘Game of Thrones’ author George R.R. Martin to his agent Ralph Vicinanza in 1993 has appeared online, after being photographed hanging in the offices of publisher HarperCollins. The letter shows some of the author’s original ideas for the series, as well as demonstrating how much Martin’s vision has changed over the years.

George R.R.Matin and GOT castGeorge R. R. Martin and the cast of HBO's 'Game of Thrones'

The Guardian reports that the letter outlined the structure for the “the high fantasy novel” Martin had promised Vicinanza, as well as revealing details about significant characters. "When completed, this will be the first volume in what I see as an epic trilogy with the overall title, A Song of Ice and Fire," the author told his agent.

The letter currently resides in the new London offices of HarperCollins and appeared on the Twitter account of bookstore Waterstones, who quickly deleted the image. The letter’s authenticity has since been confirmed by HarperCollins who told The Guardian, "We're enormously proud to have it in our possession.”

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Tyrion Lannister, Daenerys Targaryen, Arya Stark, Bran Stark and Jon Snow are laid out as the “five key players’ in the series, although their initial paths might sound unfamiliar to Thrones fans.

For example Arya, who is 9 years old at the beginning of the series, was set to ”realize, with terror, that she has fallen in love with Jon, who is not only her half-brother but a man of the Night's Watch, sworn to celibacy. Their passion will continue to torment Jon and Arya throughout the trilogy.”

Game of thronesThe characters of 'Game of Thrones'

The author also writes that "the enmity between the great houses of Lannister and Stark [will play] out in a cycle of plot, counterplot, ambition, murder, and revenge, with the iron throne of the Seven Kingdoms as the ultimate prize." However the letter is also reported to contain a blacked out final paragraph which possibly revealed too much.

But one thing that Martin hasn’t deferred from was his promise to kill off major characters. "All three books will feature a complex mosaic of intercutting points of view among various of my large and diverse cast of players," he writes. "The cast will not always remain the same. Old characters will die, and new ones will be introduced. Some of the fatalities will include sympathetic. . . characters."

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"I want the reader to feel that no one is ever completely safe, not even the characters who seem to be the heroes. The suspense always ratchets up a notch when you know that any character can die at any time," the author continued.

So far five books have been published in the fantasy series, the latest being 2011's A Dance With Dragons. It’s not clear yet when the long-awaited sixth book, The Winds of Winter, will arrive, as it was not included in HarperCollins' 2015 publishing schedule.