Moody Portrait of Compelling Couple, Antique RPPC

I love a good portrait and find these two pretty compelling. Not sure if she is his wife or his mother or otherwise, but one gets the sense she's watching over his every move, and maybe casting some judgement on the photographer, too!  Moody and atmospheric and I keep returning to study their faces, especially, again and again.

5 3/8" x 3 1/2". Very good condition, unused postcard back, early 20th c.