Wow, this was quite the epic. Captivating, really moving and so many other things.
I enjoyed following Harry's life and Snape's portrait life through the years and watching their relationship develop to a rewarding and satisfying ending.
Some of the things I loved best: Snape's and McGonagall's relationship. (And the resolution with Dumbledore.) All the details about living in a portrait. Snape's realisation of why he couldn't move on (a very intense emotional moment). The fact that our loved ones wait for us at the other side. Harry's children (especially Lily!) All the bits of ironic humour throughout. Headmaster Harry. I think my favourite part of the story was the years when Snape was assistant headmaster (and from there to the end.)
The whole story was an intense emotional ride. Well done!