If Game of Thrones has taught us anything, it's that blood doesn't guarantee power in Westeros — only an army does. Aegon the Conqueror seized six of the kingdoms not because he had a right to them, but "because he could," Jorah Mormont tells Daenerys. Likewise, Robert Baratheon didn't sit on the Iron Throne because he was more deserving than the Mad King, but because he defeated Aerys Targaryen in a rebellion.
Still, anyone who hopes to sit on the Iron Throne must win over the great houses of Westeros, and having a legitimate right to rule can do wonders to earn their support. Confusingly, though, there are now six different people who could convincingly rule the seven kingdoms. Here's how their claims break down.
Why she deserves the throne: To support Cersei's claim to the Iron Throne, you have to first believe that her husband, the "usurper" Robert Baratheon, was the rightful king of Westeros and that he launched a new dynasty after he ousted the Mad King, Aerys Targaryen, in the rebellion. When Robert overthrew the old ruler, in other words, the Targaryens ceased to have any claim to the throne.
When Robert dies in a hunting accident, his sons Joffery and Tommen are theoretically next in line for the throne — under the assumption they are actually his children. Robert's brothers, Stannis Baratheon and Renly Baratheon, claim the throne instead, alleging that Joffery and Tommen are not Robert's blood and are in fact the illegitimate children of Cersei and Jaime Lannister. Regardless, all these people are dead, as are their children and potential claimants: Stannis burns his only daughter, Shireen, at the stake before dying, while Renly is killed by a shadow monster. Joffery is murdered and King Tommen commits suicide, after which his closest living relative — his mother — becomes queen (Myrcella technically would have inherited after her brother Tommen, but she has also been killed).
Here's where things get interesting: Even if Tommen is exposed as being an illegitimate son, Cersei could potentially still be the rightful queen. This has to do with the fact that in Westeros, women do not inherit rule until the male line goes extinct. The Baratheon line of King Robert no longer exists; with no other legitimate claimants, the only option seems to be the queen dowager, Cersei.
Why she doesn't: To assert Cersei has a claim to the throne, you either have to believe that Tommen was the son of Robert (which we know he wasn't), or that Robert Baratheon was rightfully made king through conquest when he overthrew Aerys Targaryen, which Daenerys doesn't. Gendry could also pose a problem to Cersei's claim too — and we'll get there. Additionally, even as Westeros' queen dowager, Cersei technically cannot hold power because the throne belongs to the Baratheon line, which she only married into. Assuming someone in the Baratheon line should rule, then Cersei's brother Jaime should be king. Which brings me to ...
Why he deserves the throne: To arrive at how Jaime deserves the throne, you have to go back. Way back.
Again, first we have to assume Robert Baratheon created a new dynasty in Westeros when he overthrew the Mad King. By doing so, the Baratheons became the ruling family. Great. Only, as explained above, there are no more Baratheons; they're all dead. King Tommen wasn't actually a Baratheon by blood, either, and Cersei can't hold power because she's just a lowly queen dowager. So now what?
We need to find Robert Baratheon's closest living relative, which means going back a few generations. The maesters over at Mashable did some of this legwork, figuring out that "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." And who is that surviving heir? Well, somewhere along the way, Robert's ancestor, Elyanna Baratheon, married Lord Mathin Lannister. Elyanna and Mathin had children, who then had children, and eventually, one Tywin Lannister was born. Of course, Tyrion Lannister shot his father, Tywin, with a crossbow, meaning inheritance would then pass to Tywin's oldest living son: Jaime Lannister.
Why he doesn't: There's a bit of a complication, in that Jaime once took an oath to be a member of the Kingsguard, meaning he can't ever hold a title. Jaime's vow was technically for life — but Tommen also released Jaime from his oath. Still, Jaime has indicated he has no interest in ruling. There is also that whole problem with Robert Baratheon overthrowing Aerys Targaryen; just because Aerys was defeated does not necessarily mean the Baratheons get to establish their own dynasty. There is plenty of reason to argue that power should be retaken by the Targaryen family, as Daenerys plans to do.
Why he deserves the throne: If you agree that Jaime's vow was for life, or that Jaime has in any way expressed disinterest in being king, then the next Lannister son should be king. That, of course, is the brother in exile — Tyrion.
But there is another way Tyrion could potentially be the rightful ruler of Westeros. Some people believe that Tyrion is actually the son of Joanna (Tywin's wife) and the Mad King, making him, technically, a Targaryen. All this starts to add up — a dragon in Daenerys' prophetic vision is said to have "three heads," and we already know Daenerys and Jon are two of them. Tyrion make sense as the third. "Add in Westeros' deeply entrenched cultural tradition of the rights of male heirs, even bastards, above those of female heirs, and you can see how a potential Tyrion reveal could be a problem," writes The Ringer. "Would Tyrion, as the son of an actual king, come ahead of Jon in the pecking order?"
Why he doesn't: Okay, let's admit it. That whole theory is pretty far-fetched. While Tyrion superfans might hope the show will pull the ultimate plot twist by putting him on the throne, his claim is based on a lot of things we don't have proof of yet.
Why she deserves the throne: If any Targaryen is going to sit on the Iron Throne, the likeliest option seems to be Daenerys. She is the only surviving heir of Aerys Targaryen, who (you could argue) was unlawfully overthrown by Robert Baratheon.
You also have to believe there is no other Targaryen heir, a question that became much more complicated last season when we learned about Jon's origins. Yet Daenerys still might be the rightful queen. The logic, as explained in one theory on Reddit, is as follows: The Mad King Aerys had two sons: Rhaegar and Viserys. Rhaegar had two children and a wife, all of whom were killed by The Mountain. Rhaegar also secretly annulled his marriage in order to marry Lyanna Stark. Lyanna became pregnant and Rhaegar is killed, making Viserys the only heir of Aerys. Aerys is killed by Jaime, so then Viserys, technically, is king.
This is all, importantly, before Lyanna gives birth to Rhaegar's baby, Jon Snow. Before he dies at the hands of Khal Drogo, Viserys — still technically king! — names his sister, Daenerys, his successor. The thinking goes that the king's named successor would be more legitimate a claimant than the king's nephew, who wasn't even born until after Viserys had taken the throne.
Why she doesn't: Again, that theory is pretty tin-foily. What seems more likely is that while Daenerys is the only surviving child of Aerys, her older brother's legitimate son has a more rightful claim than she does. This is Westeros, and male-preference primogeniture — a system in which the claim of eldest surviving male children goes before daughters — means that no matter how directly Daenerys is the descendant of the Mad King, her male nephew should take power before her. (Then again she has a giant army. And dragons.)
Why he deserves the throne: As stated above, it seems pretty convincing that due to the way inheritance works in Westeros, Jon is the only son of the eldest son of the dead king, and therefore should be the ruler before Daenerys. If Jon had a son (uh, with someone other than Daenerys), then that child would be ruler in his stead before Daenerys. If he didn't have children and also died, then Daenerys would be the legitimate queen.
Why he doesn't: Also as stated above, all this could be voided if Viserys named Daenerys as his heir and if that overrides the claim of her nephew.
Why he deserves the throne: The best claim of all might belong to a different "bastard" — the blacksmith Gendry.
To support Gendry's claim, you once again have to go back to the debate over whether the Baratheon dynasty deserves to rule by conquest or if the Targaryen dynasty deserves to rule due to its historic claim on the Iron Throne. There's a pretty good case to be made, though, that the Baratheon dynasty is a better choice; the original dynasty can only return if it takes its throne back by force. Short of that, the Baratheons deserve to rule, which leads you to Cersei, Jaime, or perhaps Tyrion being the rightful leader. Or does it? Gendry is, presumably, the bastard of Robert Baratheon and an unknown woman. He is, nevertheless, the only surviving son of the former king, after all the rest of Robert's bastards were killed.
While Gendry's claim is complicated by the fact that he is a bastard, and bastards can't inherit, some fans think we just haven't learned his complete parentage yet. There is some suggestion that Cersei is Gendry's mother, making Gendry the only child of the king and queen, and the rightful inheritor of the Iron Throne due to his Baratheon title. Unconvinced? Gendry claims his mother would sometimes visit him in Flea Bottom, and that she had yellow hair. Cersei also tells Catelyn Stark about losing a "dark-haired" child. Even the "red priestess" Melisandre calls Gendry's blood that of a king.
Why he doesn't: Still, that's a pretty big if. Gendry himself tells Arya Stark that his mother was a "tavern wench" who died when he was young, and while believers of the Gendry theory still have an explanation for that, it seems as if all signs are pointing toward him actually being a bastard. In that case, a sitting king or queen would need to legitimize him, which, with Cersei on the throne, seems pretty unlikely.
If one thing is for sure about Westeros, though, it's that even titles you think are fixed in stone can be changed — or won. As Lord Varys wisely proclaims, "Power resides where men believe it resides." Until the season is over, we won't know who the people of Westeros choose to believe.