Marei

"Now, as it happens, Marei... is quite the spear-handler herself. She's here to thank you for staying by my side as the battle raged all around me."

- Tyrion Lannister to Podrick Payne

Marei is a character in the second, third, fourth and fifth season. She is a prostitute in the King's Landing brothel owned by Petyr "Littlefinger" Baelish.

Season 2
She is a new prostitute in the brothel owned by Lord Petyr Baelish. She is training with a male prostitute and receives instructions on how to act aroused by the veteran Ros.

Later, another customer at the brothel voyeuristically watches Marei and a male prostitute as they have sex, viewing through a spy-hole in the wall of one of the brothel's rooms.

Season 3
Marei is one of the three prostitutes hired by Tyrion Lannister to service Podrick Payne as a reward for saving his life in the Battle of the Blackwater. Marei and her colleagues are apparently so satisfied with Podrick that they decline payment, much to the astonishment of Tyrion, Bronn, Ros, and even Varys.

Season 4
Marei is the second of three prostitutes being offered to Oberyn Martell and Ellaria Sand by Olyvar. Ellaria is delighted to see that Marei is "not timid". When Oberyn asks her if she likes women, Marei says that she does, as long as they look like Ellaria, prompting the Dornish paramour to compliment Marei's good taste. She begins kissing Ellaria, but they are interrupted when Oberyn storms out of the room to confront two Lannister soldiers.

Marei later indeed services Ellaria during a private orgy also involving Oberyn and Olyvar - perhaps to celebrate the recent assassination of King Joffrey Baratheon at his own wedding. Lord Tywin Lannister then interrupts, entering the room and saying he wants to discuss political matters with Prince Oberyn in private - particularly, that he wants Oberyn to be a judge at his son Tyrion's trial, and will give him a seat on the Small Council to ensure that Dorne continues to support Joffrey's younger brother Tommen. Marei and the other prostitutes quickly leave, along with Ellaria.

Quotes
"He's handsome. You didn't tell me he was handsome."

- Marei to Tyrion Lannister, regarding Podrick Payne

Behind the scenes
Marei first appeared in the Season 2 premiere, but wasn't formally introduced and given a name until the third episode of Season 3.

As of the end of Season 4, following the death of Ros in Season 3, Marei is the most commonly recurring and still living prostitute character in the series. By this point she has appeared in five episodes across three seasons starting with Season 2. None of the other minor prostitute characters introduced in Seasons 1 or 2 reappeared afterwards (save for Ros and Shae who are now dead), and the only other prostitutes introduced in Season 3 who returned in Season 4 were Kayla the contortionist and Olyvar, the male prostitute who worked as a spy for Littlefinger.

In the books
In the A Song of Ice and Fire novels, there is a prostitute named Marei at Chataya's establishment. She is a fairly minor character, and apart from the name and the general fact that she is a prostitute in King's Landing, Marei in the TV series isn't particularly based on Marei from the books. Most of Marei's scenes so far in the TV series have no direct counterpart in the narrative of the novels. Nonetheless she is not, strictly speaking, a character entirely "invented" for the TV series the way Ros or Armeca were.

Marei in the books has green eyes, porcelain skin, and silvery hair, but is also very solemn. She is also literate. While in the TV series Bronn celebrated being knighted by having sex with Mirelle, in the books he celebrated by having sex with Marei and another prostitute named Alayaya, simultaneously.

In the TV series, Tyrion pronounces her name "Muh-ray" (with a short A), as opposed to "Mare-ay" (that is, with a long A).