They’re a fey witch who changes how they look to manipulate and prank and befuddle and seduce others. Their magic is dark, illusory, spooky, and nature based.
Some thoughts:
I Want To Be Evil - Eartha Kitt
Whatever Lola Wants (Lola Gets) - Sarah Vaughan
Trust In Me (Kaa’s song from The Jungle Book)
Curveballs welcome, no wrong answers
There are some AI music generators out there with free tiers, Suno or Udio or Minimax come to mind, you could try those out. I use AI-generated music frequently in my tabletop roleplaying games, both as DM and as a player, it’s nice to be able to whip up stuff with completely custom lyrics to fit any situation.