Update: This post, written after Game of Thrones Season 6, Episode 2, explains the legitimacy of certain events in Episode 10. We've added some brief notes based on the rest of the season, so don't proceed if you haven't seen it.

The body count in Westeros is really starting to pile up — and the return of one resurrected Lord Commander doesn't begin to make a dent in the numbers.

In Season 6's first two episodes, three of the Seven Kingdoms' most powerful leaders have been usurped and unceremoniously tossed on the scrap heap: Roose Bolton (along with his wife and hours-old heir), Balon Greyjoy (last of the participants in the War of the Five Kings and the last of the leeches burned in the fire by Melisandre) and Prince Doran Martell of Dorne (that guy in the bathrobe and wheelchair).

But the most important death is the one that barely got any attention: the poisoning of Princess Myrcella Baratheon, sister to King Tommen and official heir to the Iron Throne. She was the last Baratheon in Westeros — legally speaking, at least — and her absence has the potential to create even more of a power vacuum in Tommen's already ineffectual reign.

Image: GIPHY

If Tommen were to die without producing any offspring, there'd be no official heir apparent — a fact that doesn't seem to have occurred yet to his mother Cersei or biological father Jaime. So far, apparently, neither has thought to do what any real-life monarchy would do in this situation: assure the world loudly and often of a secure succession.

Which would be an easy and indeed pleasant duty for them — if they'd only hit the books to find out who the successor is.

(Note that this is not the case in the Song of Ice and Fire books on which the show is based. George R.R. Martin has kept Myrcella and Stannis alive thus far; he also didn't have Stannis's daughter and heir, Shireen Baratheon, burned at the stake. At this stage, the showrunners are far more murderous than the famous author.)

So who is next in line to the Iron Throne of Westeros on the show, presuming Tommen's death leads to a peaceful and legal transfer of power? The answer might surprise you. But buckle up, because we're going to need to do some serious time traveling through Westeros history.

Even in real life, royal lines of succession can be hard to grasp. First of all, it isn't simply about who is descended from whom. There are several hundred royals in Europe who have more right to sit on the throne of England than Queen Elizabeth II, for example, but they are barred by dint of being descended from the Stuarts, a line of ousted Catholic English kings.

Similarly, if the Baratheons died out, legally and politically speaking, you couldn't simply hand the Iron Throne back to Daenerys, daughter of the Targaryen king that King Robert Baratheon ousted. Once a new dynasty seizes a throne, there's no going back except by force. And Dany's chances of doing that are looking pretty slim at the moment.

Sorry Dany, Dragons don't count when it comes to the line of succession. Image: HBO

So to find out who would replace Tommen, we have to go through a convoluted Baratheon family tree, find out who married whom, and end up in another House altogether.

But first, a side note: Yes, technically there is a son of Robert Baratheon still alive in the show. His name is Gendry, the only one of Robert's bastards to survive Cersei's massacre. But he is still a bastard, and to ascend to the throne he'd have to have the current king legitimize him.

That's hardly likely, of course, even though Gendry has Baratheon blood in him and Tommen (secretly, sort of) doesn't. The air in King's Landing is thick with irony.

Robert Baratheon

King Robert and his lethal drinking horn. Image: HBO

The leader of Robert's Rebellion acquired the throne by force. He had three kids, officially and legally at least, with Queen Cersei. Joffrey and Myrcella are dead, leaving only Tommen — and if the prophecy Cersei received from a witch is to be believed, the other blond-haired kid isn't long for this world either.

The Throne would then pass to Stannis Baratheon, if he weren't pushing up daisies near Winterfell, then his faithful daughter Shireen Baratheon, if she weren't in cinders, then his younger brother Renly Baratheon, if he weren't in an advanced state of decomposition post-shadow baby.

That exhausts this generation of Baratheons. And according to this unbelievably extensive Baratheon family tree, you have to go all the way back to Robert's great-great-great-great-grandfather to find anyone in his family who sired another line that survived.

A hundred and fifty years before Robert was even born, an aristocrat called Corwen Baratheon married a woman named Leyne and had six kids. One of them, Arion, was Robert's great-great-great grandfather. The next one down to have surviving kids was Elyanna, who married a Lord named Mathin. Lord Mathin Lannister.

Mathin fathered Jason, who fathered Demon, who fathered Gerold, who fathered Tytos Lannister. And who was Tytos' firstborn son?

Tywin Lannister

If you were still alive, you'd be here by now. Image: HBO

Yep, that's right. The old puppet-string puller, Lannister Godfather and Hand of the King could have sat on the Iron Throne in his own right! That is, if he hadn't ended up looking down the business end of Tyrion's crossbow while sitting on the commode.

That being the case, however, his title of heir to the throne of Westeros passes to his firstborn son ...

Jaime Lannister

He's alive and intact! Well, apart from that right hand. Image: HBO

There's a problem here, however — Jaime is Lord Commander of the Kingsguard. That's a lifetime post, one you don't simply leave, even if it is to become King. Cersei may want him to rule, but we get the sense that Jaime's sense of honor wouldn't let him leave the Kingsguard even if the small council bent the rules for him.

Update: Jaime was removed from the Kingsguard by Tommen in order to help the Freys capture Riverrun. In theory, that should make him Tommen's heir — which might explain why he didn't look too happy at Cersei's coronation.

So if Jamie is passed over for the post, what about Tywin's second-born son?

Tyrion Lannister

'King Tyrion, first of his name' has a ring to it. Image: HBO

Though a peaceful transfer of power to the Imp would be one of the most delicious things we could ever witness in a future Game of Thrones, it's also less likely to happen than Jaime's ascendancy.

You may remember that small matter of Tyrion being convicted and sentenced to death for regicide. He's officially a traitor who lost his trial by combat thanks to an overly-cocky Red Viper.

Even if that somehow didn't legally bar him from the throne, even if his exile thousands of miles away were no impediment and even if he didn't have Mereen to rule over, Cersei would personally slit every throat in Westeros before she'd let her little brother wear the crown.

Besides, Tyrion has made friends with dragons now. What does he need with a dumb throne made of sharp swords?

So unless the Imp intends to steal those dragons from Daenerys and seize power with them himself, the title of heir to the throne of Westeros passes to ...

Cersei Lannister

No longer just Queen Mother. But at what cost? Image: HBO

Yeah, you read that right. Tommen's rightful heir to the Iron Throne, the next ruler of the Seven Kingdoms if he doesn't get busy with Margaery, is his own mother — via the most convoluted route of succession imaginable.

Did we just blow your mind?

It doesn't just make sense from a genealogical perspective. It would also be storytelling dynamite.

Picture it: Cersei, fearful of the prophecy and utterly torn apart by the deaths of all her children, is forced to take their place on the throne as she mourns. The ultimate underhanded player of the game of thrones would win it, ironically, by legal means. And the victory would taste like ashes in her mouth.

Perhaps the only sweet part about it for Cersei would be the ability to lord over Margaery again, presuming Margaery will be freed from the Sparrows' clutches at some point. That scene would be the exact opposite of one from Season 5, and would be worth it just to see Cersei swilling her giant wine goblet and destroying her rival with a devastating put-down.

Update: Now we know Cersei was able to remove the threat of Margaery as part of her attack on the Sept — which may not have left time for a vengeful put-down, but was certainly effective.

Is any of this likely to pass? Not necessarily. The whole of Westeros is under threat from a winter nobody has prepared for, and from the once-in-a-thousand-years civilization-ending threat of the White Walkers. To the east, even if there is no invasion fleet any more, there be dragons enough to cause serious damage. And Dorne, post-coup, is likely to be in full-scale rebellion.

The Baratheon-Lannister dynasty's chances of retaining control of King's Landing in the face of all those enemies seems vanishingly slim. But if the show and the books have taught us anything thus far, it's that you never, ever count this family out.

Update: Turns out the "Cersei becomes Queen" scenario was more likely than we suspected. But now you know it was a legitimate ascension to the Iron Throne, and not a coup by the Queen Mother.

BONUS: Bran of House Stark takes you inside the mighty 'GoT' treasure room