Really digging the amount of work you've put up here. Very cool man.
The scar in the last one is neat but I think it would have much more impact if the lips were skewed slightly where the scar is. After getting slashed like that, a long stroke, the cut must have been somewhat deep and the lip outlines would not match up as nicely as they do now, they would be offset a touch. Looks like you may have painted a scar over normal lips. Also think of how the stitches would have affected the lips. Always keep in mind "cause and effect." It will always help the piece have that much more impact to the viewer.
I'm almost saying this more for myself as I need to think more like this as well
Keep it up, great stuff.