While touring the Great Sept of Baelor in King's Landing, King Joffrey Baratheon explains to Margaery Tyrell that Rhaenyra Targaryen was eaten by her brother's dragon while her son was force to watch.
In the books
In the A Song of Ice and Fire novels, Aegon II took the Iron Throne at the behest of Lord Commander Criston Cole of the Kingsguard, thereafter known as Criston the Kingmaker, even though his father, Viserys I, intended Rhaenyra to succeed him. Rhaenyra disputed his ascension and claimed the throne for herself, leading to the civil war known as the Dance of the Dragons. Aegon managed to defeat his sister, and fed her to his dragon. Shortly thereafter he died himself, leaving no male heirs, which led to his nephew Aegon III, Rhaenyra's son, taking the throne.
- Aegon II Targaryen at A Wiki of Ice and Fire (spoilers from the books)
|Lord:||Queen Daenerys Targaryen||Heir:||None|
|Title(s):||King of the Andals and the First Men|
|Ancestors:||Aegon the Conqueror · Visenya · Rhaenys · Maegor the Cruel · Jaehaerys I · Rhaenyra · Aegon II · Aegon III · Baelor the Blessed · Viserys II · Aegon the Unworthy · Naerys · Daena the Defiant · Rhaena · Elaena · Daeron the Good · Daenerys Martell · Myriah Martell · Baelor Breakspear · Aerys I · Aelinor · Rhaegel · Maekar I · Aerion the Monstrous · Aegon the Unlikely · Duncan the Small|
|Current members:||Aemon Targaryen|
|Deceased members:||Aerys II Targaryen · Rhaella Targaryen · Rhaegar Targaryen · Elia Martell · Rhaenys Targaryen · Aegon Targaryen · Viserys Targaryen · Drogo · Rhaego|
|Household:||Ser Jorah Mormont · Ser Barristan Selmy · Rakharo · Kovarro · Aggo · Irri · Doreah · Jhiqui · Malakho · Missandei · Grey Worm · Daario Naharis|