Eglantine

Eglantine is a background character in the second season. She is played by an unidentified extra and debuts in "The North Remembers." Eglantine is the septa at the Red Keep acting as governess of Princess Myrcella Baratheon.

Background
Eglantine is a septa of the Faith of the Seven. She serves at the Red Keep in King's Landing as governess and companion to Princess Myrcella Baratheon.

Season 2
Eglantine is among the royal entourage for a tourney to celebrate King Joffrey Baratheon's nameday.

Eglantine watches over Princess Myrcella as she plays blind man's buff with two courtiers.

Eglatine can be seen in the boat accompanying Princess Myrcella, now a ward of House Martell, at her send off from King's Landing as they travel to Sunspear as part of the betrothal arranged by Princess Myrcella's uncle Tyrion Lannister of Princess Myrcella to Prince Trystane Martell.

In the books
In the A Song of Ice and Fire novels, Septa Eglantine is a loyal servant of the royal family and Princess Myrcella Baratheon. She accompanies Myrcella as part of her retinue when she is sent to Dorne as part of the marriage alliance arranged by Tyrion Lannister with House Martell.