|Theories may be removed if ...|
In her youth, Cersei Lannister received a prophecy from Maggy the frog that she would die at the hands of the "Valonqar", which is the word for "little brother" in High Valyrian. No one person has been confirmed to fill this role; given the circumstances, it could refer to anyone who is a younger sibling.
Several of the people hypothesized as the Valonqar are younger sisters, because it is not solidly established that the word must refer to a male sibling. It is entirely possible that Valonqar is a gender-neutral term; that High Valyrian uses the male gender when gender is actually unknown; that Maggy is not fluent enough in High Valyrian to know or to correctly employ the gender differentiation; that she is actually speaking one of the dialects of the Free Cities that might not completely agree with High Valyrian regarding this word; although Septa Saranella's translation  may have been wrong, a Tyroshi who brings Cersei a dwarf's head claiming it to be Tyrion's refers to him as her 'valonqar' , it is still possible from this that valonqar may be gender neutral, but it's meaning of 'younger sibling' at least is confirmed. As a result, the Valonqar is generally considered to be only slightly more likely to be a man than it is to be a woman. It is worth noting that the name "Maggy" is itself suspected to be a misrepresentation of the title of Maegi.
People suspected of being the Valonqar include:
- 1 Tyrion Lannister
- 2 Jaime Lannister
- 3 Aegon Targaryen
- 4 Daenerys Targaryen
- 5 The surviving Stark-children
- 6 Stannis Baratheon
- 7 Brynden Rivers
- 8 Tommen Baratheon
- 9 The Sand Snakes (except Obara)
- 10 Sandor Clegane
- 11 Trystane Martell
- 12 Brienne of Tarth
- 13 Loras Tyrell
- 14 Garlan Tyrell
- 15 Gendry/Edric Storm
- 16 See Also
- 17 References and Notes
Tyrion Lannister is the youngest brother of Cersei. Cersei treated Tyrion poorly from shortly after his birth, and suspects him of being the valonqar. Tyrion blames Cersei for Mandon Moore's attempt on his life and for the slanderous testimonies during his trial.
Jaime is Cersei's twin brother, but was born after her, and is therefore her younger brother. They have shared an incestuous relationship since youth, but drifted apart after Tyrion's trial.
Aegon Targaryen, son of Rhaegar Targaryen and Elia Martell, was the younger brother of his sister Rhaenys Targaryen. Rhaenys and Elia died at hands of Lannister forces. If the person claiming to be Aegon really is Aegon, he has plenty of reasons to want to kill Cersei.
Daenerys Targaryen was the younger sister to her brothers Rhaegar and Viserys and as one of the contenders for the Iron Throne also has plenty of reasons to kill Cersei.
The surviving Stark-children
After the death of their parents and older brother Robb all of the Stark Children (Bran, Sansa, Rickon and Arya) have reasons enough to kill Cersei. Arya has gone as far as to include Cersei on a list of people she wishes to kill. Valonqar means Little Brother in High Valyrian, but Maester Aemon tells Samwell that he was a fool when thinking of the Prince Who Was Promised Prophecy. He should have remembered that High Valyrian is gender neutral and it could have been Princess Who Was Promised. Valonqar is no different. It doesn't mean Little Brother. It means Little Sibling. Jon Snow calls Arya "little sis" repeatedly. They both think of it throughout the series whenever they recall each other. Also, Arya is being trained in the ways of the Faceless Men. The Strangler is a poison they use regularly and Arya has already used it. Prophecies are rarely direct. If Little Sis uses the Strangler to kill Cersei it will be a fulfillment of Maggy's prophecy.
Though Bran is crippled, his warging ability means he could kill Cersei. Because of his youth Rickon seems unlikely, but it's also possible that he could kill her through his direwolf.
Stannis is the younger brother of Cersei's former husband, King Robert. He is attempting to overthrow Cersei.
The valonqar passage was a fragment of Maggy's response to Cersei's third question, regarding her, and king's, children. Thus it could be read as "you will see all your children die, and then the youngest will kill you". That would require Tommen to die, rise from dead and only then strangle someone to death, like Ser Waymar Royce in the series' prologue.
The Sand Snakes (except Obara)
The Sand Snakes are the daughters of Oberyn Martell and nieces to Elia Martell, both were killed by the hands of the Lannister-man Gregor Clegane. All Sand Snakes have reasons enough to kill Cercei but because of the circumstance that Obara isn't a younger sibling to anyone she won't fit the prophecy. Her younger sisters Nymeria, Tyene, Sarella or possibly Elia could be candidates, the other three Sand Snakes seem unlikely because of their youth.
Sandor Clegane is the younger brother to his sibling Gregor and was for a very long time in service for House Lannister, at least as Joffrey Baratheon's sworn shield and member of the Kingsguard. During the Battle of the Blackwater he deserted and encountered Arya Stark. He travelled together with her through the devastated Riverlands until he was left behind by Arya after he was badly wounded. His fate is unknown until now. Some believe that he is still alive. If he is, he could also be the Valonquar because of his despise for the Lannisters.
Trystane is the younger brother to Arianne and Quentyn Martell. As part of a marriage pact orchestrated by Tyrion Lannister, he was betrothed to Myrcella Baratheon. Cersei planned to kill him as part of a plot to get her daughter back to King's Landing. If Trystane would get knowledge of this he has another reason for revenge besides the fact that his uncle and aunt died by the hands of the Lannisters.
Brienne was the younger sister to her brother Galladon and in the service of Renly Baratheon, who challenged the Lannisters, and Catelyn Stark who was murdered in an assassination orchestrated by Tywin Lannister. Tasked to find the daughters of Lady Catelyn and to protect them she could decide to kill Cersei as a kind of protection.
Loras is the younger brother of Margaery, a likely candidate for the "young queen" mentioned earlier in Maggy's prophecy. He and Cersei have a rivalry at court, as he is a champion of Queen Margaery and Tommen's favourite among the Kingsguard. Cersei sent him to lead the battle for Dragonstone, hoping he would die in the attempt; he is reported to be alive but badly burned.
Garlan is the younger brother to Willas, the heir to Highgarden, and the older one to Margaery and Loras. Because of the mistreatment of his sister (humiliated by the Faith Militant) and younger brother (badly injured during a attack on Dragonstone), both events caused by Cersei, he has good reasons to kill her.
Gendy and Edric Storm are the bastard-children of Robert Baratheon and younger siblings to others, for example Mya Stone who was the first bastard Robert sired. They both survived the purge of Roberts several bastards in King's Landing because they were not present. But as long Cersei is alive, no one of both would be ever safe, so killing her could be a goal for both of them to protect themselve.