Vaegon is the bastard child of Rhaenys Velaryon and Viserys Targaryen. She is heir to the Iron Throne against people's judgement. Due to Aemma Targaryen passing and Viserys older age he calls upon Vaegon his only heir that can only according to him and Otto Hightower reproduce future heirs. Vaegon is G!P! VaegonxRhaenryaxAlicent