I've seen effective portraits in which the subject is looking away, or presented in profile, and while I can appreciate them I find it very, very difficult to take portraits myself where the subject is not looking back into the camera; looking at the photographer; by extension, looking back at the audience for the work.
Part of the joy of selecting your own subjects instead of always working a assignment or commission is that you get to lead the collaboration in a different way. There is an unwritten rule in an exchange of time that both the subject and the photographer will get to try poses or styles (within the range of the photographer's stylistic comfort zone) they each want rather than adhering to the desires of only one party.
When I select portrait subjects, and invite them into collaboration, I am making selections by looking at their eyes and a certain range of interesting expressions. If I can't capture their eyes the way I want to see them then the image generally fails for me even though the same image may work wonderfully for my artistic partner of the moment.
In this instance Rebecca and I were mostly on the same page and the poses and styles we experimented with fell into a narrow range. This is also an example of something that commenters on a previous portrait post discussed, the subject-to-camera distance and the role of longer focal length compression in portrait creation.
I was using a Sony A7rii and a Rokinon 135mm f2.0 lens. The original frame was horizontal and I positioned the camera to fill the frame as you see it, from top to bottom, knowing I would be cropping the sides. In effect it is at the position that worked best for me in terms of composition and compression. I could have moved back a bit if I wanted more compression and then used the generous resolution of the file to crop in but I could not have moved in any closer without disrupting the exact frame and the amount of compression I wanted to end up with.
I chose a shooting location that would allow me about 35 feet from Rebecca to the back wall. I knew I wanted to work with a wide aperture and was looking to accentuate the fall-off in focus. Additionally, I brought my lighting modifiers in as close as I could to her while still keeping them out of the frame. The 50 inch circular diffuser that represented the main light source (LED Light) was only inches above her head and slightly to the front of her. The close proximity of a large source is largely responsible for the soft skin tonalities and the prominent shadow under Rebecca's chin.
It's one of my favorite ways to light a portrait.