I said I met her again, but that may be an exaggeration. Let me explain.
The conquest of Angband, though quick, was a bloody one, and I watched the commander of the fortress from afar. His fighting style was hauntingly familiar; I had thought only a student of mine could use such thrusts, such blows, such deathly precision. I am well and humbly aware of the fact that no one has ever rivalled me in the use of arms and none ever shall. But this black shadow came the closest. Yet our army was the stronger one, and swiftly we pushed him to retreat. I longed, then, to test my skills against his, but I think he was wise enough to know it would be the end of him, for he escaped into the very bowels of Arda, and we lost track of him. As it was, we were in a hurry to destroy the power of his master.
You might think this has nothing to do with Anna, but hear me out: You know I have good eyes. It was not difficult to discern the features of my enemy, for his helm had no visor. From beneath it flowed some stray curls of hair the colour of flames. And I saw his eyes. They were the a deep blue. The shape of his face also reminded me faintly of Anna.
I had no doubt I was looking at her son, and even less did I doubt the name of his father: Morgoth himself.
Yes, I can understand your doubt. It should be impossible for two ainur to have children between them. Yet Morgoth must have found a way, the evidence was plain as the light of the Trees in front of my eyes. Sauron, Anna's son. Gorthaur the Cruel, child of such a gentle maiden. Destroyer of Nations, born to a maker of beautiful things.
Yet I say I met her in him. Somewhere in those eyes I felt her presence. But I kept her secret, for I wished not to stain her fair name, nor did I think the information would be of any use to my superiors. And I was not fooled by my feelings; he was my enemy no matter who his mother had been.
I say 'had been', for I felt she was dead. Or rather, I felt she lived on in her son, and in him only. After all, she had not returned to us.