Forgive me if my comment isn't exactly coherent, but it's quite late at night and I'm feeling a little breathless at the moment. This was... breathtaking, in the best and most poetic sense of the world. I legitimately stopped breathing when they hugged, because it was such an intimate and fragile moment.
I'm in awe at the layers of characterization you've put into this, both while exploring their grief and betrayal, and in the smaller bits of worldbuilding (like Holmes' hiding places and Mary's passion for drawing).
"A while became forever" is possibly one of my favorite lines in this fic, it hit me like punch in the guts.

An incredible fic, thank you anon, this was a pleasure to read!