What color tweaks keep a somber painting from looking flat?

[David98]

I’ve been working on a painting where the foreground figure is meant to feel isolated, but my usual muted palette just makes the whole piece look flat and dreary instead of intentionally somber. I’m worried that if I introduce more vibrant colors for contrast, it’ll completely break the emotional tone I’m aiming for.

[NoraBD]

I tried a tiny splash of color on the hands and a bit on the lips and it helped the eye find the figure without destroying the mood.

[Riley_H]

I kept the background cool and mute and slipped a warm edge where the light hits the figure a little, just enough to carve it out.

[James79]

Could the problem be the light direction rather than the color?

[Zachary2]

One time I tested a warm glow on the figure and kept the rest colder. It helped the person feel a touch closer but the room still read flat in photos.