I'd offer redlines and such, but it would make it so much easier on me if I had a tablet. xD
For
Rehn: it looks like the frame of her face was going to be kinda angled to make it look like she's looking off in some direction at first, but you went with a frontal view instead. The left side of her face (that's on our right side) has a bit too much curve and makes it look a bit awkward, so level it out to be more like the other side of her face.
Move her left eye (that's on our right) inward, and her mouth and nose seem to be very tiny. I think you should enlarge those more.
For
Iru: Her face looks too small for her head, actually. And this is where I show you this
guide here, since I can't work well with MSPaint.
And that last one, I think her behind is angled strangely in relation to her legs' positions. And if her shoulder is kinda pulled back, you should be able to see a bit of an outline where her scapula is.
Hope this was useful for you. :3