Some of those "If Only's" were gut wrenching, but luckily there was a fantastic one waiting as well. I really love that you had Severus take his time in coming around to the idea (and being seduced by the idea of Penseivesmut) of being with Harry fairly slowly. Sometimes hate goes to love too quick for me but I guess what I'm saying is that you convinced me!
I thought the part after Severus woke up was perfection. Just enough little touches and looks for us to know things were going to work out, which is what I love!
Also, I have to mention my love for Albus trying to reiterate Snape's importance in the whole war effort. You've created a really lovely story, one I know I'll be thinking about for some time to come!