"Stay strong and grow strong, you will move mountains if you do"- Olenna to Shawn
Lady Olenna Tyrell, née Redwyne, is the elderly matriarch of House Tyrell. Lady Olenna has been a master of court politics and intrigue par excellence throughout her life. She's also known for her wit and sarcasm. As a result, Lady Olenna is popularly nicknamed the Queen of Thorns, in reference to the Tyrell sigil - a rose - and her cutting barbs. In many ways she is the de facto head of House Tyrell at the time of the War of the Five Kings and appears to hold a great deal of influence over the Reach.
After most of her family are killed in the Destruction of the Great Sept of Baelor, an event orchestrated by Cersei Lannister, Olenna's desire for vengeance leads her to pledge House Tyrell's forces to Daenerys Targaryen.