Duncan Albert

Duncan Albert is a boy from Alison's past who might hold the answers to the girls' questions. Duncan claims he flew Alison from Hilton Head Labor Day weekend, although Ali had claimed she took the bus home.

Season 2
In "Father Knows Best," Aria gets cold while investigating in Brookhaven and dons Alison's former Vivian Darkbloom signature red coat. With her dark hair spilling over her shoulder, Aria is mistaken for Vivian. She turns around to meet Duncan.

It is revealed in the episode "Eye of the Beholder" that Duncan met Ali/Vivian in a book store in Brookhaven, a couple of stores down from the creepy doll repair shop, which could possibly mean that he is part of the trail to "A." Duncan confides this information to Aria in a meeting on the Rosewood High School grounds.

Duncan tells Aria that Vivian often spoke about her four friends. When Aria presses him about whether she discussed anyone she might have been afraid of, Duncan seems unwilling to talk to her about it at her school. He reveals that he and Vivian met up at a place near Brookhaven quite often during the summer Alison disappeared. He also reveals that he knew Vivian's real name was Alison. When Aria reveals that Alison is dead, Duncan rises and turns away, visibly upset and heart-broken.

During a follow-up meeting with Aria, Duncan takes her up in his plane. He explains that he and Alison used to fly often and that she used to feel free, safe, and in control (presumably from "A") while up in the air or flying the plane herself. He said that Alison never revealed to him who she was afraid of. He even has Aria take the wheel for a while.

He also mentions that he might have been in love with Alison, if someone (Ian Thomas) hadn't been in the way. Duncan also tells Aria that he was with Alison the day she went missing. He explains how she called him, and he picked her up from Hilton Head, dropping her off in a field near Philadelphia, revealing that Alison was in town, 6-7 hours before she met up with the girls who believed she had supposedly taken a taxi from the airport.

In "If These Dolls Could Talk," when Spencer tells Alison, which could or could not have been a dream/hallucination, that Aria spoke to Duncan, and he said that he took her from Hilton Head the day she died, back to Rosewood, Ali responds, "He talks too much."