What if Elia had twins instead of just Aegon?
What would change if Elia had twins instead of Aegon? It was hard to tell how many children a woman was pregnant with in those days. Plus, Elia was in frail health. They could easily think Elia was carrying only one child then discover the truth when the babies are born.
We know Rhaegar is already in Dorne with Lyanna at this time. Lord Commander Gerold Hightower arrives at the Tower of Joy. He informs Rheagar that Prince Aegon and Princess Visenya were born silver-haired and purple-eyed, hale and hearty. The prophecy has come true - Rhaegar has fathered the three heads of the dragon.
Now what?
What does this do to Rhaegar's idea of Ice and Fire?
What happens to Lyanna? Is she pregnant at this point?
What happens with the war? Has Jon Arryn raised his banner?
What other ramifications are there to consider?