The Morgendorffers are plunged into a nightmare when Quinn goes on a date and disappears - turning up in hospital after an assault (revealed to be by Skyler Feldman). The crisis forces Daria to come to terms with her stormy relationship with Quinn.
Pollard stated in the author's notes that he saw the fanfic as explaining how Quinn ended up as she did in Daria's future story in "Write Where It Hurts": "For many people, it's a sudden, traumatic event that triggers a change in the paths on which they lead their lives."
This fanfic is discussed in several essays focusing on fanfic using Quinn's rape as a plot device, including "On the Subject of Quinn and Rape" by Kara Wild and "Controversy More Than Ever" by CINCGREEN, which both argue the trope in general implies Quinn 'had it coming' and Wild felt it was being used to 'redeem' the character. CINCGREEN more aggressively accused "Sins" of arguing this. Pollard's position was that he certainly did not intend to make such an argument, and any interpretation contrary to his intention is an incorrect interpretation.
Sins of the Past at Outpost Daria Reborn
Sins of the Past at FF.net