“Game of Thrones” isn’t done with George R.R. Martin’s source material. While the writers of the HBO drama have outpaced the books in certain storylines, they still have a major part of Book 4 to cover: Jaime Lannister’s (Nikolaj Coster-Waldau) trip to Riverrun. Reports indicate Season 6 will likely bring in this part of the books.

Brynden Tully/The Blackfish (Clive Russell) will return in Season 6, Watchers on the Wall and Los Siete Reinos reported. He hasn’t been seen since the Red Wedding, but Russell apparently was spotted on set with Coster-Waldau and Jerome Flynn, who plays Bronn. The three of them filming together is a pretty strong indicator they’ll be showing the siege of Riverrun. So far, they’ve filmed a scene with Jaime and Blackfish having an argument, as well as an action scene where Blackfish is launching flaming arrows.

Jaime’s journey to Riverrun is a huge part of his story in “A Feast for Crows,” the fourth book in the “A Song of Ice And Fire” series, but it wasn’t clear if it had been cut from “Game of Thrones.” Jaime went to Dorne in Season 5 in a storyline created for the show, and only the writers knew where his story would go from there. However, audiences started to speculate a return to the riverlands storyline could happen once set photos started to surface, ComicBook.com reported. Pictures of a castle with a drawbridge and the trout sigil of House Tully were posted on Instagram in September, and they seemed to indicate Jaime would at least pay a visit to the riverlands.

The addition of this arc excites readers not only because of Jaime’s scenes, but the possible introduction of another beloved book character. A plot in Riverrun could easily pave the way for Lady Stoneheart to be introduced, the Huffington Post speculated. Fans of the books have been waiting for the undead version of Catelynn Stark (Michelle Fairley) to appear, but it isn’t clear if “Game of Thrones” has cut the storyline or if they’re just waiting for the right time to introduce her.

Even if Catelynn doesn’t return, at least two of her family members will. Bran (Isaac Hempstead Wright) will come back in Season 6 after a year-long absence, and Jon Snow (Kit Harington) has been spotted on set despite what appeared to be a death scene in the Season 5 finale.

“Game of Thrones” Season 6 returns to HBO in 2016.