EWoT:Daved Hanlon was Captain of the Queen's Guard in Caemlyn and a Darkfriend.
Captain of the guard
Under Moghedien's orders, Hanlon reports to Mili Skane. She shows him the price of failure by killing Jaichim Carridin and torturing Falion Bhoda. She tells him to become one of Elayne Trakand's men. Hanlon begins working as a guard for Elayne under the alias Doilin Mellar. When she is attacked by three men, he fends them off, leading to a promotion to Captain of the Queen's bodyguard.
When Elayne becomes pregnant, most everyone in Caemlyn speculate that he is father because of his status as Captain, a rumor which she does not squelch in favor of the truth: that the Dragon Reborn is the father. 
Hanlon leads a sortie out of Caemlyn against orders, to help save and bring in a group of Lord Luan Norwelyn's men. This angers both Elayne and Birgitte Silverbow as Luan hasn't declared his support for Elayne yet. Hanlon is reprimanded in public for it, in turn incurring his wrath.
After his audience with Elayne, he heads to a meeting with Mili, killing a man who was sent to follow him. When he arrives at Mili's place, he shares information with Falion, with whom he has come to an information exchanging truce. During his meeting, Mili orders him to free the captive sul'dam in the palace and to carry on burning Caemlyn's food warehouses.
He is with the mercenary captains, when they demand more gold from Elayne. Elayne sends him on to his duties, embarrassing him in front of the captains. After having him followed by Samwil Hark, Elayne has Hanlon arrested and questioned.
Escape from Caemlyn
Eldrith Jhondar and Temaile Kinderode break into Chesmal Emry's cell and are confronted by Elayne. All three woman end up shielded and as Elayne is making her escape, she is stabbed by Mellar. He makes Chesmal Heal her and Elayne ends up incinerating her. He manages to grab one of the copies of Matrim Cauthon's Foxhead medallion making him impervious to Elayne's Weaves. He stabs Temaile and slits Eldrith's throat stating he is under orders. Elayne starts tearing the ceiling down but he manages to make his escape with the medallion.
During the Last Battle
He and his group of mercenaries ambush Elayne and Birgitte disguised as refugees. They kill most of the guard and Mellar kills Birgitte. They capture Elayne and try to demoralize her troops by hailing her death. He is resistant against her weaves due to having stolen one of her copied foxhead medallion ter'angreal. As Hanlon was beginning to cut her children from her womb, he was killed by Birgitte, who was reborn as a Hero when the Horn of Valere was sounded.
Min Farshaw sees him in the rebel camp of Toram Riatin, Caraline Damodred, and Darlin Sisnera. She has a viewing, seeing him surrounded by "bruised hues so dark they seemed almost black". She says it indicates violence and that he will murder any in his way, and warns Caraline not to trust him. - fulfilled Hanlon is revealed to be a Darkfriend.