Question: how are aerys and rhaegar targaryen related?
Answer: Prince Rhaegar Targaryen was the eldest son and heir of King Aerys II Targaryen, by his sister-wife Queen Rhaella Targaryen. ... Over time, this massive inbreeding led to a strain of insanity appearing in the Targaryen bloodline - culminating in Rhaegar's father, Aerys II, who is best remembered as the Mad King.