Riddles in the Downs

[Nerwen]

Galadriel55– another very clever answer. But as you point out yourself, the first line would be a stretch. The answer to this riddle betrayed a certain, specific lord, and played a more immediate role in "defeating shadow".

I did wonder if someone would guess Fëanor, though.

And again, you're also taking the right approach (in a different way).

[Pitchwife]

Is it Húrin?

Faithful I - his epithet Thalion, the Steadfast, and his resistance to Morgoth's attempt to win him over;
yet I my lord betrayed
To serve the one who wielded shadow - "Turgon, Turgon, remember the Fen of Serech!", giving away the location of Gondolin to Morgoth's eavesdropping spies;
Shadow I helped defeat. - hmm, maybe by covering Turgon's retreat from the Nirnaeth so that Eärendil could be born and raised in Gondolin?

Patient was I - sitting on Thangorodrim all those years, forced to watch Morgoth TV;
but rash move I made.
Madness tore me - could refer to his dealings with the Woodmen in Brethil, or to the affair with Thingol and the Nauglamír;
now at last I
Know what it is to sleep. - finding ease of his torments in death; part of Morgoth's curse was that he couldn't die before Morgoth released him.

[Nerwen]

No, it is not Húrin. However, that is the best guess yet, and more the right sort of answer.

Originally Posted by Pitch

Faithful I - his epithet Thalion, the Steadfast, and his resistance to Morgoth's attempt to win him over;

(...)

now at last I
Know what it is to sleep. - finding ease of his torments in death; part of Morgoth's curse was that he couldn't die before Morgoth released him.

Again, this is not the solution, but you're right in looking for someone for whom those lines have particular significance.

Also, remember what I said earlier: there are a couple of "trick" lines; what I might call riddles-within-a-riddle. Working out what these really mean would be a great help to you.

*smiles mysteriously*

[Urwen]

The Unhappy?

Faithful I - Well, he was faithful till the kidnapping
yet I my lord betrayed - for sake of his wife
To serve the one who wielded shadow - Sauron,sort of
Shadow I helped defeat. - He warned the son of his lord of incoming danger; also, were it not for his treachery, the biggest couple of First age may not have met each other and Silmaril would still be with Morgoth

Patient was I - He always returned to check on his wife
but rash move I made. - One day, he heard her calling, rushed to see her and thus was captured etc.
Madness tore me - Grief for his wife
now at last I
Know what it is to sleep. - died

I explained all the lines!

[Nerwen]

Originally Posted by Urwen

I explained all the lines!

Yes, you did, my dear, well done– only it isn't Gorlim. About time someone guessed him, though. I thought it would be much earlier.

You are now verrrry warm.

But remember– trick lines!

[Galadriel55]

Um, Wormtongue?

Faithful I - as Gandalf said, for many years he served Theoden faithfully, as he could
yet I my lord betrayed
To serve the one who wielded shadow - aka Saruman
Shadow I helped defeat. - killed Saruman
Patient was I - gradually loosening Theoden's will and "poisoning his thoughts"
but rash move I made. - Maybe how he spit at Theoden?
Madness tore me - Killed Saruman when he was...pretty angry
now at last I
Know what it is to sleep. - well, he constantly had to be vigilant with his "master", be it Theoden or Saruman. When he died, it must have been something of a relief not to constantly be on the watch...

[Nerwen]

...but no, it is not Wormtongue. That's getting colder again... look at my replies to the last two guesses.