"Invisible Black" Or "Low Key" Post-Processing?

[rdhousehold]

I am looking for direction on how to give the following look in post-processing if possible. I understand the invisible background technique is commonly done with camera settings and a flash but is it possible to get the look with a regular photo? I've tried using the selection tool and lowering the exposure on the background outside of the selection but I want a little more of the faded look if that is possible to manipulate? 

The photo is one I found on google and he had a video showing how he did it but it was blurry and I think with photoshop.