New Challenge: Title Track
Tolkien's titles range from epic to lyrical to metaphorical. This month's challenge selected 125 of them as prompts for fanworks.

The story of Eönwë, Maia of Manwë, and Mairon Aulendil after the War of Wrath. A tale of darkness, light, love and betrayal over the Ages of Eä.
Tolkien simply told us that [Sauron] fell back into evil, for the bonds that Morgoth had laid upon him were very strong. But this line is unsatisfactory on so many levels that it became a challenge to create a plausible background story for Sauron's fall, from the time Eönwë returns to Aman to face the Valar over his decision to free one of Morgoth's most dreaded minions to Sauron's final fate, long after the destruction of the Ring.

B2MeM 2011 and 2012 participant
MEFA 2011 1st Place - Incomplete: Drama & Smaug's Treasure (but complete since then!)

The story of Maedhros' captivity in Angband, his rescue and his recovery is in the Silmarillion treated in a few paragraphs. This is a fleshed-out account of the events that may have befallen between Maedhros' imprisonment and his return to his old life... as far as that is possible.
Occasionally drifting into AU territory, depending on how closely you follow the source (WHICH source? :P).
The usual warnings apply - particularly to chapters marked with an asterisk.
Part One completed.
Part Two completed.
Part Three, Chapter 10 added: In which the reconciled Noldor make plans for the future. End of the trilogy.

This is the story of the unequal friendship between Maedhros and Uldor and its bitter end in betrayal and death, told from Uldor’s point of view.
It does not say anywhere that they were friends that I know of, but it seemed a reasonable explanation to me of what happened before Nirnaeth Arnoediad. Otherwise, wouldn’t the sons of Feanor have to have been a bit slow on the uptake or the sons of Ulfang fiendishly clever?
Like the rest of the series, this is, strictly speaking, Maedhros/Fingon, but it is possible to ignore that aspect of it (Uldor himself never guesses), so I’m not marking it.
This story has been nominated for the MEFAs 2010 by Angelica and won Third Place in Races: Cross-Cultural: General. Thank you very much to Angelica and to everyone who reviewed it for the MEFAs!
Now illustrated by the wonderful Alasse:

The captivity of Maedhros on Thangorodrim, and his subsequent rescue by Fingon. This is actually part of my modern AU - the elves are living in the modern world and the events in Middle Earth are told as a flashback.
Warnings for rape/non-con, torture.

Maedhros is tormented in Angband by Sauron and frees himself from Sauron by submitting to Morgoth.

Not everyone involved with the sacrifices at Armenelos were believers.

Maedhros want to die on Thangorodrim, Fingon won't let him.

A young Elf joins Maedhros's personal staff, and in the course of his duties discovers some disturbing facts about his childhood hero. Graphic violence, disturbing themes.

Maeglin at the fall of Gondolin. Graphic violence and adult themes.

A view of the Kinslaying through Maedhros's eyes. Warning: violent and disturbing imagery.

A detailed retelling of the Nargothrond element of the lay of Leithian from the points of view of Finrod and Orodreth.

During the attack on Sirion, Maglor is reminded of past deeds. (300 words)

Maglor makes the perfect harp.

Finarfin assists with the re-embodiment of his son Finrod.

Celegorm fell first at Doriath and heard not the call of Mandos. He watches his two brothers fall in turn, and then his spirit finds two children in the forest, where he will realize his final purpose.