Aegon the Younger
Rhaenyra and Daemon's elder son, rider of young Stormcloud — a boy with two crowned kin killing each other over the chair he sits nearest to.
A soul of House Targaryen, born at Dragonstone.
The fuller tale
Their story
Rhaenyra and Daemon's elder son is born into a household already crowded with half-siblings and rivalries not of his making, and given, while still a boy, a young dragon named Stormcloud to grow alongside — a bond the family clearly intends as an investment in the next generation's strength, whatever the current one's wars cost it.
Too young through most of the Dance to be more than a name kept safe and a claim kept in reserve, he nonetheless sits, by simple accident of birth, disturbingly close to a chair that two branches of his own family are actively killing each other over — a child whose future the war's outcome will determine long before he has any say in shaping it himself.
How it ends for them
The chronicle records no death for this soul — they are living when the tale leaves them, or their ending is a page the maesters have yet to turn.
Their chapters, book by book
Fire & Blood — The Dance of the Dragons 1 chapter that name them
Where the page and the screen part
Aegon the Younger's role in both tellings is largely confined to his parentage and his dragon rather than any independent action, and the two versions track closely on the facts available — the differences that exist are chiefly matters of how much screen time and narrative attention the ongoing show chooses to give a character who, in the book, remains a minor figure throughout the war's main action.
Their journey
Where the two tellings send them to the same place the road runs whole; where they part, the screen keeps the left and the books the right.