Was Jon Snow's birth legitimate?

S07E05: Would that person be the rightful heir to the Targaryen throne when they were born, even if Viserys had ascended to the throne before they were born?

Inheritance law

The law is Agnatic Primogeniture, not Agnatic Seniority.

A grandson of an older son stands before a younger son in the succession of a king.

If the older son has no sons, the throne passes to his younger brother.

We have nothing in the history of Targaryen where king died and grandson came to the throne (except when Jaehaerys I died and Viserys I came to the throne), but we see that this is the Westerosi law, Agnatic Primogeniture. Lord Elmo Tully became Lord of Riverlands when his grandfather died (his father had already died).

So so:

  1. Oldest son
  2. Sons of the eldest son in order of age
  3. Younger son

This Agnatic Primogeniture Law is why we have a free society called Second Sons. Second sons don't inherit, so they sometimes join this mercenary company to carve their own fortune. Viserys is a second son, as is Bran. Bran told Ser Rodrik that he will never be Lord of Winterfell because after Eddard that will be Robb and after him Robb's sons.


What happens when the cup is over?

So what if Viserys inherits the throne before Jon is born?

Regardless, even if Viserys took the throne, Jon would still be his uncle's heir until a son was born to Viserys. Jon's mere birth wouldn't cause Visery's dethronement, but he would be an attractive option for lords looking to depose his uncle.

When Viserys becomes king, the line of succession will be established in relation to him, not his father. So after Agnatic Primogeniture, Jon would still be his uncle's heir as the closest male relative. But once a son is born to Viserys, Jon will go down one by one. Since Jon did not exist when his uncle was crowned and anointed Lord of the Seven Kingdoms, he cannot claim that the succession was invalid. Or maybe he can if he wants to make his claim, but opponents will point out that the cup is over and is now being passed to Viserys' brood, as Jon didn't exist then.

However, this is not canonical of my speculation, as there is no such case in canon where an uncle came to the throne while a nephew was in the womb.

The next example would be that of Torgon Greyiron the Latecomer. When his father Urragon III died, he was outside the Iron Islands. Iron Islanders choose their kings over Kingsmoot. His brothers named a Kingsmoot without inviting their eldest brother. The Ironborn elected Urrathon IV Goodbrother to be king.

When Torgon returned he claimed he was not there to assert his claim so the succession would be invalid as he was the strongest claimant. He successfully deposed Urrathon IV, albeit at gunpoint.

This is the best possible example of an applicant appearing after a successor has taken place. But Ironborn are different. Their laws are different. Greenlanders instead follow the bloodlines.


Great advice

This seems like a good case for a fourth Grand Council.

If the succession is unclear, a grand council is convened at King's Landing in which all lords elect the new heir or king. So far there have been three major councils (only two aimed at choosing a new heir / king), which resulted in the election of Viserys I and Aegon V.

Now suppose everyone knew about Lyanna and Rhaegar and that she was pregnant and lords decide to wait until their child is born (to determine the gender, if it is a woman, the throne definitely goes to Viserys ) and convene a council to choose the heir.

The precedent of the 3rd Great Council shows that lords would rather choose older uncles than little nephews with better claims than choose King Aegon V in place of his nephew Prince Maegor, even though Maegor was the son of Aegon's older brother Aerion.

If so, Viserys would most likely win. But the problem here is, Lords feared that Maegor might have inherited his father's madness, Prince Aerion, which led them to turn to his uncles Aemon and Aegon. Viserys was known as a frightened child who hid behind his mother's skirts and was prone to erratic behavior. Not to mention, Viserys was a minor herself, unlike Aemon and Aegon who were adults. In our case, Viserys is more like Maegor, so Lords might be inclined to choose Jon instead and form a Regency Council to handle statecraft until Jon can reach adulthood.

However, this will only happen if Viserys has not been crowned. If he were crowned, it would be his turn to convene a Grand Council on Jon's birth. If he doesn't, a line will be made for him.


The next case in the real world

We have a real case. This is from Shapur II of Persia. When his father Hormazd II died, he was still in the womb. His older brother Prince Adur Narseh inherited the throne.

As a result of uprisings and conspiracies by nobles against the emperor's cruelty, Shah Adur Narseh was murdered, his second brother was blinded, the third was imprisoned but fled to the Roman Empire. With no other option, Lords of Persia turned to the unborn Shapur II.

According to tradition, the crown of the Persian Empire was placed on his pregnant mother's pudenda, and the throne was reserved for the unborn child. (This is disputed by some historians because the child's sex could not be known and if it was a girl, she could not ascend the throne).

The unborn child ruled for seventy years, the longest reign of any Persian emperor, and became one of the greatest emperors of Persia.

SIMEL

Does that have to do with the fact that the Viserys were not officially crowned? Or would Jon be crowned and dethroned Viserys at birth, even if Viserys was already serving as the reigning king?

SIMEL

There was a time when Rhaegar was dead and Jon was not yet born. During that time, Viserys was the rightful heir and if he rose during that time what would happen when Jon was born?

Aegon

@ SIMEL Yes, Viserys was the Crown Prince in that short time between Trident and Sack of King's Landing. After that he was Viserys, third of his name, King of the Andals and the Rhoynar and the first men.

SIMEL

@Aegon, but in this case the "head of the house" mug was already given to Viserys when the mad king was killed. Wouldn't that work the same way?