It’s not a light arrangement that you see too often, but it has its purpose, especially in film and comics. Because it places equal importance on the light side and the shadow side, it can convey the sense that the subject is a doppelganger, a person whose soul is a battleground of equal and opposing forces.Like this fellow, for instance.
One thing you get with split lighting is reflected light bouncing back into the nasolabial furrow (the smile crease). This bounced light is very warm because it comes off the nose, so the N.L. furrow will likely be the warmest skin tone in the face.
