Fanfics that focus on angst are usually a bit depressing. They feature our couple in situations where they're sad, in pain, or just generally have a rough time. These fics are good when you're in a tough situation yourself. Angst fanfics often contain the death of a major character, and are almost always dark.
Duo's Worst Nightmare By Chemiclord. After suffering some insults to her image, Hilde decides that she'll improve her body, even if she has to starve herself to do it! Will Duo be able to save her and convince her of her own beauty before it's too late? Warnings: Mature Themes.
Darkness and Light, Heaven and Hell By the Fablespinner. Very dark, somewhat depressing Duo/Hilde fic! Very nice though! Warnings: Strong Language/Death of a Major Character.
Life Goes On By Lady Leiwe. Duo has died and Hilde must now deal with her feelings about the death of the love of her life! Warnings: Death of a major character.
Defying Death By Lara Winner. Go Lara! Write more please! I just love her fics! This one is pretty long, and hard to describe. Very good! Warnings: Death of a Major Character/Mild Language.
I Promise By Lara Winner. After Duo's untimely death, Hilde struggles with her feelings and her desire to be with Duo. Warnings: Death of a Major Character.
Soul Searching By KLMeri. Long after Hilde disappeared from Duo's life, she finally decides to go home, but is Duo still waiting for her when she returns? Warnings: None.
Demons of Night By KLMeri. Duo is being haunted by nightmares, but when Hilde tries to help him, he rejects her, causing her much more pain that he even realizes! Warnings: Uh... a TINY bit of domestic violence.
Sorrow By KLMeri. As Hilde is dying alone, she thinks upon Duo and regrets not telling him all her feelings. Warnings: Death of a Major Character.
Loneliness By KLMeri. Sequel to "Sorrow" in which Duo thinks upon Hilde's death. Warnings: Death of a Major Character.
To Say Goodbye By Miyu. Very sad fic from 's Point of View. Warnings: Death of a major Character.
Learning to Deal By Princess RaJa. Very clever fic! Hilde is suffering and Duo can't figure out why. What's worse, Hilde seems to be ignoring him and won't even talk to him! Warnings: Death of a Major Character.
Learning to Live By Blondie. Hilde's health is deteriorating as Duo struggles to accept the fact that she may not pull through this illness. Warnings: Death of a Major Character.
I Thought She Knew By Ami. Hilde doesn't realize how much Duo loves her and she leaves, but will be Duo be able to get her back in time? Warnings: VERY MILD Language/Death of a Major Character.
Why? By Lyo. As Hilde lay in the hospital after being injured in the last few episodes, Duo questions himself and his feelings for her. Very well written! Warnings: Mild Language.
Colder Than Ice By Lyo. Another VERY good fic by Lyo in which Hilde runs away after an argument with Duo. Will Duo be able to find her before it's too late? Warnings: Language.
Perfect Weapons By Lyo. This is the sequel to Colder Than Ice. Lyo is such a great writer! Please read! Warnings: Language/Violence/Death of a Major Character.
December 31 A.C. 199 By Valkyrie. Great New Years fic! After Hilde discovers a ... disturbing secret about her new boyfriend, Duo and the rest of the gang help her though her problems! Warnings: Language/Hints of child molestation and homosexuality.
Chapter One, Chapter Two, Chapter Three