The "Game of Thrones" Season 7 finale titled "The Dragon and the Wolf" was without a doubt one of the most important episodes of the entire series. The title itself suggested that we were about to have confirmation of Jon Snow's true identity. And so we did, in the form of Bran's vision which confirmed that Jon's parents, Lyanna Stark and Rhaegar Targaryen, secretly married in front of the Heart tree, making Jon the true heir to the Iron Throne.
Also, we got to see Lyanna revealing to Ned that the baby's name is Aegon Targaryen. And that seemed to bring confusion among the fans since we know that Rhaegar already had a son named Aegon with his lawful wife, Elia Martell.
However, with the help of the "A Song of Ice And Fire" book series, we can at least try to explain why this might be.
The dragon has three heads
As a part of her House of the Undying visions, Daenerys saw her brother Rhaegar talking with his wife Elia about their baby. "Aegon," he said, "What better name for a king?" And when asked whether he will make a song for him, Rhaegar replied that he is the prince that was promised whose song is the song of ice and fire. But in the end, Rhaegar said that there must be one more since the dragon has three heads.
What happened next?
After being told that Elia couldn't survive another labor, Rhaegar needed to find another woman to bear him the third child. And what better candidate than the she-wolf herself -- Lyanna Stark?
Perhaps in the meantime, he realized that it was supposed to be Lyanna all along. After all, she is ice, and he is fire, so it seems that their son will be the prince that was promised who is the son(g) of ice and fire. Keeping in mind that Rhaegar was obsessed with this prophecy, it stands to reason that he would name this child Aegon as well, firmly believing that that should be the name of a prophesied hero.
What about Jon Snow?
We already know that Robert's Rebellion was built on a lie and that Rhaegar and Lyanna were actually in love, but it doesn't erase the fact that hundreds of thousands of people died because of their love. With that being the case, one has to wonder: Was it worth it?
To answer this question, we must return to the present-day and Jon Snow's important role in the upcoming War for the Dawn. And following Rhaegar's logic, the casualties of Robert's Rebellion were a small price to pay for Jon Snow's birth since he would grow up to be the legendary hero who will save mankind.
