I was listening to a song I like in many forms - Tamlyn. I'd never heard Frankie Armstrong before. Fairport's version was my first listen, and will always be my favorite. But this was a fine folkie rendition.
An accompanying note said 'Lady Margaret saves her true love from the faeries.' And that reminded me of an Aoife O'Donovan song - Magic Hour. (I suggest listening to the acoustic version first, without the visuals, to see how different the video is from your vision. For me, it was jarring! youtube.com/watch?v=sQToTtqxalc )

Next watch the video, created and directed by Bodine Boling, with a background in fantasy/ sci-fi. It has a very spooky ending.
https://www.youtube.com/watch?v=B3eaxEG03nQ   
I assumed it meant she was a spectral angel, guiding the child, taking him 'home' in the final frame. An angel of death. I tracked down Bodine and asked her. She had a better answer - in Norse stories, gods sometimes watch over humans. If they get attached, they may take them away, as their own lovers or play things. I really liked that vision. Either way, he had no choice in the end.

Aofie has become a favorite musician for me. Old Time, folk, Americana... Or banging away at a Wurlitzer, sounding a bit like Brian Wilson! Enjoy