(What TV advertisement was that from? Margarine, I think?)
"High Key" is a term photographers use to describe a composition in which the subject is the darkest part of the image. Your eye is drawn to the subject by being different than the rest of the image. In this image, Mercy is the darkest part of the image, and her eyes are the darkest part of her... so the viewer's eyes are innately drawn to them. The is ideal!
Mid key and low key images are far more common. They feature predominantly mid or low key (dark) surroundings and the viewer's eye is drawn to the person by being lighter than everything else.
A few years ago, new photographers were snapping images with bright sky and dark terrain. I knew that would be a passing fad as it did not follow innate art principles. You can't fight nature.
It's fine to experiment, but in the end, there's a REASON artists use time-tested principles in leading the viewers' eyes where the artist wants them to go.