He is the HEIR to Highgarden,
the future of House Tyrell.
Game of Thrones Season 6, Episode 7
"until the HEIR come of age."
Game of Thrones Season 1, Episode 7
Just the parts he'll use to make his HEIR,
Game of Thrones Season 5, Episode 10
but he was the rightful HEIR
to the Seven Kingdoms.
Game of Thrones Season 1, Episode 7
The Faith arrested the HEIR to Highgarden.
Game of Thrones Season 5, Episode 6