According to Entertainment Weekly, the additional spinoff is in the capable hands of Thrones co-executive producer Bryan Cogman and A Song of Ice and Fire author George R.R. Martin — who is also co-writing at least one of the other “successor shows.”
Cogman has worked on Thrones since its first season and has written several stand-out episodes, including season seven’s “Stormborn,” season four’s “The Laws of Gods and Men” and season three’s “Kissed by Fire”
There are not yet any details available about the plot of this new prequel, but as a whole, the offshoots are slated to explore time periods in the world of Westeros before the events of Thrones. However, Martin has revealed that two fan-favorite narratives are not under consideration: Robert’s Rebellion and The Tales of Dunk and Egg.
“We’re not doing Dunk & Egg,” he wrote in a blog post on LiveJournal. “We’re not doing Robert’s Rebellion either. I know thousands of you want that, I know there’s a petition… but by the time I finish writing A Song of Ice & Fire, you will know every important thing that happened in Robert’s Rebellion. There would be no surprises or revelations left in such a show, just the acting out of conflicts whose resolutions you already know. That’s not a story I want to tell just now; it would feel too much like a twice-told tale.”
The four writers previously announced are Max Borenstein (Kong: Skull Island), Jane Goldman (Kingsman: The Golden Circle), Brian Helgeland (Legend), and Carly Wray (Mad Men, The Leftovers).