Agravaine

Agravaine, a character in the Guinevere book, is a Knight of the Round Table. He makes his first appearance in Chapter 4.

Appearance
Agravaine has long black hair and a braid with half of his head shaved, brown eyes, and a light stubble. He wears a brown leather armor.

Personality
You describe Agravaine as iced-eyed. According to Lancelot, Agravaine has never been much for friends, but he has always been tolerated by his cousins - Mostly by Morgana and Gareth, and less by Gawain. Lancelot says that he's far from kind, and based off his betrayal, he's also not a loyal person.

Guinevere

 * Chapter 4: Tangled Threads
 * Chapter 5: By Sword and Lance
 * Chapter 9: A Knight's Oath
 * Chapter 13: Bound
 * Chapter 14: Camelot's Fall (Mentioned; Physical Appearance Determinant)
 * Chapter 15: A Kingdom Asunder
 * Chapter 16: Threads of Fate

Morgana
Morgana and Agravaine are cousins, and Agravaine was Morgana's champion during the joust in Chapter 4. According to Lady Delilah, he and Morgana are close. He is eventually defeated at the end of the joust by whoever you chose as a champion.

Arthur/Artura Pendragon
Arthur/Artura and Agravaine are cousins, but according to Lady Delilah, Agravaine has no love for him/her or Lancelot. When the masked assassins attack Camelot in Chapter 9, Agravaine rides ahead and tries to stop them in the name of the King/Queen and Camelot. However, a premium Chapter 13 scene reveals that he was involved with the attack, and only did it so that no one would suspect him.

Lady of the Lake
If you see the vision of how the Lady of the Lake was trapped beneath the lake, you discover that Agravaine was the one who did it. At first he called out to her under the guise of a request, but when the Lady of the Lake appeared, he stabbed her with a knife imbued with powerful and dark magic. If asked why, Agravaine says it wasn't personal, possibly hinting that someone else put him up to it. In Chapter 14, that person is revealed to be Merlin.

Lancelot du Lac
Lancelot and Agravaine don't like each other. If a premium Chapter 13 scene is taken, you find out about Agravaine's betrayal and Lancelot afterwards locks him up.

Trivia

 * His character model resembles Jackson Walker from The Royal Romance series.
 * His crimes include treason, attempted murder, and conspiracy to commit murder.