I don't know much about Bainbridge other than that she is Australian singer from the '90s and is most famous for her "Mouth" song. Her music sounds mostly to be piano and maybe some guitar and bagpipes...her song "State of Mind" might even have some drums in it. Her songs tend to be slow, her voice sensual and low, exotic-sounding, like she's trying to draw one in with her beauty and then she's going to strike them down. Her songs are calming, easy to sing to, and "nice."
Carol of the Bells is the only dark-ish piano song I can think of. Most of the rest are too...chipper or slow. Beethoven does offer a few excellent choices, but for the most part, piano music is so dry. (I hope no lover of piano is reading this...) Troy was the only person I know to make up his own dark-sounding, fast-paced music. We even dated for a bit. I could listen to him for hours but decided not to--in the end-- for the sake of my indepedence.
The one band to not have let me down thus far is Korn. They constantly are changing their music so that it's never the same yet distinctly them. Jonathan's voice is original, like so many others...Serj Tankian comes to mind.
We will continue our search for the dark pianist, and I am sure we will find him or her eventually...feel free to leave me tips if you know of any.