Wow. I don't know how I managed to forget to comment on this the first time around, but I was looking through your art (because sometimes I just have a pressing need, okay?) and found it again.
Love the dark circles under their eyes. Love the grey in Snape's hair and beard. I also really love their skin tones in this They both look so tired - Harry waiting and patient, Severus wary.
Have I mentioned before that you do things with hair (on the head and facial hair) that I just didn't think were possible? Amazing.