'Game of Thrones' season 7 spoilers, plot news: Gendry to return to GoT? Joe Dempsie spotted in Belfast

The fate of Gendry (Joe Dempsie), who was last seen rowing away from Dragonstone in the season 3 finale of "Game of Thrones," has been one of the biggest mysteries in HBO's popular fantasy drama.

But rumor has it that this could change in the upcoming "Game of Thrones" season 7.

According to Watchers on the Wall, Dempsie was spotted by a reader in Northern Ireland's Belfast City Airport earlier this week. Much of "Game of Thrones" is filmed at the Titanic Studios in Belfast. In the last few weeks, various "Game of Thrones" cast members, including Sophie Turner (Sansa Stark), Maisie Williams (Arya Stark) and even "Thrones" alum Jason Momoa (Khal Drogo) have been spotted in the city.

Watchers on the Wall said that the fact that Dempsie doesn't seem to have any other projects in Belfast could only mean that the actor is there to shoot for the upcoming season of "Game of Thrones."

As fans know, Gendry, who seemed poised to become a major character in the first three seasons of "Thrones," is Robert Baratheon's (Mark Addy) only surviving child. Thus, he has a claim to the Iron Throne even if he is just a bastard. In season 3, Ser Davos Seaworth (Liam Cunningham) saved the boy from Melisandre (Carice van Houten), who had intended on using him as a sacrifice to ensure Stannis Baratheon's (Stephen Dillane) victory in the War of the Five Kings.

Ever since Ser Davos put him on the boat and instructed him to row towards King's Landing, Gendry's whereabouts have been unknown. But a Reddit user on the "Game of Thrones" subreddit had a suggestion about where Gendry may turn up in season 7.

"I believe we will cross paths with Gendry again in Oldtown when Sam (John Bradley) starts his studies as a Maester," Reddit user Sethg119 wrote. "I believe that Sam will study the creation of Valyrian Steel and will require a smith. He will then go to the smith that resides in Oldtown who will be no other than Gendry," the user added.

Apart from Gendry becoming a smith in Oldtown, there are also theories that the young man could emerge as a major player in the final two seasons of "Game of Thrones."

As fans recall, before Gendry got caught up in the game of thrones, he was working as an apprentice for a smith named Tobho Mott in King's Landing. Tobho happened to be one of the last remaining armorers who knew how to work with Valyrian steel, which was revealed to be one of the only two things that can kill White Walkers.

Did Tobho teach Gendry how to work with Valyrian steel?

Many years ago, "Game of Thrones" author George R.R. Martin was asked this same question. "Interesting question," was his vague reply.

"Game of Thrones" season 7 will air on HBO in 2017.