Question: how are rhaegar and the mad king related?
Answer: Prince Rhaegar Targaryen, the last Prince of Dragonstone, was the eldest son and heir to King Aerys II Targaryen, the Mad King. He was the older brother of Viserys and Daenerys Targaryen and the husband of Elia Martell, with whom he had two children, Rhaenys and Aegon.