In the A Song of Ice and Fire novels, Dareon is an apprentice singer from the Reach, sent to the Wall after being caught in bed with a daughter of Lord Mathis Rowan. Even though Dareon maintains that she was waiting for him naked and helped him into her room, she named it rape under her father's eye.
He's also an excellent singer, known to sing for the Watch during dinners; Maester Aemon describes his voice as "honey poured over thunder." Jon describes him as "quick but afraid of being hit."
In "A Feast for Crows" Jon sends Dareon alongside Sam, Gilly and Maester Aemon to Oldtown via Braavos, hoping that Dareon's singing would encourage recruitment to the Night's Watch. Dareon, however, spends his time in Braavos whoring and drinking. Sam finds Dareon in a brothel, where he married a whore. Sam confronts Dareon for breaking his vows and demands that he return with him to the inn where they stay, but Dareon teases him. For the first time in his life, Sam loses his temper and beats Dareon up, and is thrown from the brothel. Sam, Gilly and Aemon leave Braavos for Oldtown without Dareon.
Arya followes Dareon to a dark alley, slits his throat and loots his body. It is the first time Arya murders in cold blood someone who never did any ill to her, her family or her friends, and did not threaten or provoke her in any way. She justifies her deed by claiming that Dareon was a deserter of the Night's Watch, but it is doubtful that Arya - who dissociated herself from her past life, thus no longer considered as Stark or Westerosi - had the right to act as the prosecutor/judge/executioner, and the way she killed Dareon did not resemble even closely to a formal execution. After committing that murder, Arya is given the milk that makes her blind.