How is House of the Dragon's Oscar Tully related to Catelyn Stark from Game of Thrones?

Things are finally starting to move ahead for Daemon Targaryen (Matt Smith) and the armies of the Riverlands. In the penultimate episode of House of the Dragon's second season, "The Red Sowing," Daemon received an important visitor at Harrenhal: Oscar Tully (Archie Barnes), the new lord paramount of the Riverlands following the death of his elderly grandsire, Grover Tully. Oscar came on behalf of his vassals to treat with Daemon, who has become very unpopular in the region after Ser Willem Blackwood (Jack Parry-Jones) commits a bunch of war crimes on his behalf.

Oscar wasted no time showing why he's the right person to lead the Riverlords. In his first negotiation as Lord of Riverrun, he managed to reassure most of his vassals that he understood their grievances against Daemon, recommitted to upholding his grandfather's oath to Queen Rhaenyra (Emma D'Arcy), and ordered the death of Willem for his vile acts. Oscar even forced Daemon to lop off Willem's head himself, since he was the one who ordered the Blackwood knight to use underhanded tactics against House Bracken in the first place.

Hearing Oscar talk about the importance of oaths right before he instigated a beheading brought back memories of Game of Thrones in the best way. House of the Dragon is firmly centered around the Targaryens, but Oscar gave us a big reminder that the loyal Tullys and Starks are still around in this era and are every bit as badass and true to their word as they were during Thrones.

Watching the episode may have even brought to mind Catelyn Tully, who became Catelyn Stark after she married Ned Stark, or her daring uncle Ser Brynden "Blackfish" Tully. If so, you may be wondering how exactly Oscar is related to the Tullys of Game of Thrones.

How is Oscar Tully related to Catelyn?

Unlike some of the other great houses in Westeros, the history of the Tullys is not painstakingly recorded by author George R.R. Martin. In The World of Ice and Fire, Martin writes about a few important eras of Tullys, such as those who led the house during Aegon's Conquest, or Oscar and his immediately family who fought in the Dance of the Dragons. But to date, the Tullys have never gotten a detailed family tree the way House Targaryen, House Stark, or House Lannister have.

In the books, there are a few more Tullys at play during the Dance than in House of the Dragon. We have Grover, the elderly grandsire. His son is Elmo Tully, who is an adult at the start of the Dance. Elmo has two children, Kermit and Oscar. Kermit eventually becomes the Lord of Riverrun after Elmo dies, and he and his loyal brother Oscar bring House Tully to the height of its power by fighting for Queen Rhaenyra.

The show has streamlined the Tully family tree for the Dance. Instead of Elmo and Kermit, we just have Grover and his young grandson Oscar, who is now Lord of Riverrun.

As for how Oscar is related to Catelyn, Lysa, Brynden Blackfish and Hoster Tully, the exact details are lost to time. This is all The World of Ice and Fire says of the Tully reign following Kermit (who is being replaced in the show by Oscar):

"[Kermit's] successors ruled as best they could after him, but Riverrun was never again as prominent as during those years. Loyal to House Targaryen through all the Blackfyre Rebellions, House Tully finally soured on the dragon kings during the madness of King Aerys II Targaryen, and Lord Hoster Tully joined Robert Baratheon and his rebels and helped bind together the alliance that brought Robert to the Iron Throne by granting the hands of his daughters to Lord Jon Arryn of the Eyrie and Lord Eddard Stark of Winterfell."

There are a few other Tullys throughout A Song of Ice and Fire lore, though. Lord Medgar Tully ruled Riverrun during the first Dunk & Egg novella, which takes place around 90 years after the Dance of the Dragons. He rode during the tourney at Ashford Meadow, so we may even meet him in HBO's next Game of Thrones spinoff, A Knight of the Seven Kingdoms! By the time of the second Dunk & Egg novella a few years later, Medgar had died and Riverrun was being ruled by his son, who was still an 8-year-old boy.

The only other named Tully we have to work with for the family tree is Celia Tully, who was betrothed for a time to Jaehaerys II, the father of the Mad King. She was the daughter of the ruling lord of Riverrun at the time, who is never named in The World of Ice and Fire. According to the sleuths over at A Wiki of Ice and Fire, that Lord Tully is either the father of Catelyn's father Lord Hoster, or the ruling Tully directly before him who succeeded Medgar.

Without any information about the relationship between Medgar's successor and Hoster, we can't say for certain whether Hoster was his son, a brother, or some other Tully relation entirely. That means all we've got is guesswork. But considering that House of the Dragon takes place roughly 180 years before Game of Thrones, there are likely quite a few unrecorded generations of Tullys between Oscar and Medgar.

If that all sounds a bit confusing, welcome to the Riverlands! People die a lot in that war-torn part of Westeros, and they don't keep strict annals like they do in the Red Keep or at Winterfell.

Perhaps we'll find out more about Oscar's relation to the Tullys of Thrones whenever George R.R. Martin publishes The Winds of Winter, the long-awaited sixth book in his series. In the meantime, House of the Dragon airs its season 2 finale this Sunday on HBO and Max.

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