Encyclopaedia WoT: Fearil

He is a Darkfriend.

He is tall, lean and quite pretty. He has pale hair and a harsh voice. (CoT,Ch24)

When Cadsuane and her party leave to find Rand, the Aes Sedai who were prisoners must leave their Warder behind in Cairhien. (WH,Ch23)
Bartol, Rashan, Vitalien and Fearil give distance and direction for Logain, Bashere and their forces to Travel to find Rand. (CoT,Ch23)
Fearil makes a private report to Elza. She orders him to kill anyone who might threaten the Dragon Reborn. (CoT,Ch24)
Elza and Fearil accompany Rand to his meeting with the Daughter of the Nine Moons. (KoD,Ch27)

In Crossroads of Twilight
1. CoT,Ch23 - Erian and Sarene report to Rand and Cadsuane that their Warder, Rashan, Bartol and Vitalien, have Traveled from Cairhien and are nearby. Elza acknowledges that Fearil is also with them.
2. CoT,Ch24 - Elza has spent twenty years cultivating the rumor that she and Fearil are married. That way no one questions their private meetings.