Disclaimer: Characters belong to Tolkien, as do the larger events (The Great Music, the Rebellion, Melkor's pardon and the like). The details are my own.
For The Old Songs' Sake
They ask why I did it, the Noldor. When they return, when they wake up again in my brother's Halls, they ask why. Why I pleaded for Melkor's pardon, back in the days when they still lived here. They tell me I should have known better, that I should have seen he could never be Good. They say that I'm too kind-hearted, blinded to reality by my tears. I think they forget, sometimes, that I am not like them. I don't have a choice about what I am, what I do. I am, and always will be, Nienna the Weeper, Nienna the Compassionate. And to the Noldor, I'll always be Nienna who unleashed Morgoth upon the world.
They don't understand, can't understand, how hard it is to see him like this. Very few of them have gone Bad, and those that do, like Fëanor, tend to end up dead shortly after. They don't know what it's like to see someone you knew like a brother locked away for Age after Age, to listen to his pleas, his curses, his threats, and to remember how he used to be.
Oh, I won't deny it, Melkor was always a little strange. Even back in the Timeless Halls, before the Great Music, he was always wandering off by himself. Perhaps our Father knew, even then, what he would turn out to be. But Eru did nothing to prevent Melkor's wanderings, and I'll admit that that did influence my decision.
But it wasn't just that. After all, he might have done nothing just to be sure that we would create the Trees, and have assumed that we would then lock the renegade away. No, there was more to it, as there always is.
He used to sing with me, when he was around. Our Father was always calling us, the Ainur, over, asking us to sing before him, singly or in small groups. Sometimes he would ask for us by name – I think that was how he chose to influence the marriages that would come later, as I know Manwë and Varda were up there together a lot. More often, though, he'd simply put out a call – 'Ten for a song, please', or something like that.
Now, I was never much of a one for singing, not like dear little Vana, bouncy thing that she is. But occasionally I did go over, just to keep at a reasonable level of skill for whatever it was Father had planned – the Great Music, as it turned out, though we didn't know it at the time. And often, when I did, Melkor was there too, singing alongside me.
At first, I assumed he was just very enthusiastic, but that wasn't true. I don't think I ever saw him sing when I wasn't there. They tell me now that it was all a way for him to gain power over me – one of the Noldor even told me, quite firmly, that Melkor had known he would be imprisoned, and that he had charmed me so I would let him out. But I don't think that's true. I think he did genuinely like me, in his own way. He may have been Dark even then, as they say, but I know what he did, keeping me company throughout those lesser Songs, was Good. Perhaps it was the only Good he ever did, but I saw it, and that is why I begged for his pardon.
So I will tell them, the Noldor, next time they ask why I let Melkor go, why I set into motion the events that led to the death of the Trees, the Kinslaying, and all the terrible wars back in the Old Country. I'll answer their questions, rather than letting it all slide past me.
I'll tell them I did it for the old songs' sake.
Yes, I admit it, I believe that Melkor/Nienna would have worked if things had gone differently.