Lighting for cave scene

[dashinvaine]

I've been a silly person and embarked upon turning a line drawing into an oil painting, without really knowing what to do about the lighting or colours. The scene is a knight rescuing a captive woman, deep in an unlit cave, where she had been kept by nasty reptilians called Gargers. It's intended for the cover of a fantasy graphic novel, the rest of which will be line drawings. I want the figures to stand out quite well. Oviously nothing can be too bright, but I don't want the figures to appear to be luminous either. (But he's still got to look the arhetypal knight in shining armour). Are there any lighting/tonal tricks that can enhance the clarity and dramatic impact of the composition while retaining credibility?
Original drawing upon which the piece will be based:

[Viridis]

Honestly, this probably fits in better in the Critique forum than Art Discussion.

However, I'll give you a few tips.

The first is to fix those stalagmites, as they don't look much like actual cave textures at all. Go get some good reference on stone in general and caves in particular.

For the lighting issue, perhaps the knight carries a lantern in with him? That gives you an easy light source. Or perhaps you could have very faint glowing lichen? It depends on how deep in the cave they are-- glowing lichen tends to happen only deeper in caves.

There are a couple options, but you could start by doing research on caves and perhaps you'll find more ideas that way.

[dashinvaine]

Thanks. On relfection it probably would be better if this thread were moved to WIPs or the critique section. Meanwhile here's a start on the painted version. Settled upon a suggestion of light from the right, behind the figures...