I speculate that Euron Greyjoy is the son of the Mad King. Euron wants revenge for House Targaryen. He views Daenerys, Valyrian culture, and House Targaryen very highly, because he has Valyrian blood. The Hightower’s are the ones who killed the dragons, and caused the Dance Of The Dragons. According to the YouTuber Preston Jacobs. Euron has a deep hatred for the Faith Of The Seven, and especially Old Town. Even Barbrey Dustin points to a Maester-Faith-Hightower Conspiracy. The Hightower’s are major players in the Game Of Thrones. A secret puppet masters that control the system. Eurons wants to destroy House Hightower, and bring down this corrupt system that is responsible for making his childhood miserable.