I think it's interesting how the two big holidays we celebrate today have completely exchanged places over their lifetimes.
When it started, Towel Day was very much a memorial. The date - May 25th - has no textual significance whatsoever. Rather, like the feast day of a Saint, it is the anniversary of Douglas Adams' death. The observance with the towels and all is/was a Fandom reference, but the purpose of the holiday was to honor the memory of a Great Man - and how more appropriately than with a bit of silliness? And in the, what is it, 20? more? years since his death, the memorial aspect has been eroded away, until it is now basically a celebration of the work more than the man, fun unalloyed by grief, a way to fly your geek colors. And perhaps that's what he would want in the end.
The Glorious 25th of May is exactly the opposite. It is - or was - purely a Fandom thing. It's a holiday in text, and we celebrate it alongside the characters because, well, Night Watch is a frickin amazing book and deserves to be celebrated. And there's admittedly always been a melancholic aspect, deriving from the text itself, but the date and the celebration were ultimately fictional. What I used to say is that I celebrated both, but I celebrated Towel Day harder because it commemorated something real.
And then Terry Pratchett died.
And this silly fandom thing we were already doing proved a ready made memorial to honor the memory of a Great Man. The fan art now us bursting with lilac covered fedoras. It now celebrates the man in addition to (perhaps even more than) the work.
I always wondered if Pratchett chose May 25th in honor of Adams. And I wonder what this day will look like in another 20 years, when the grief of this death has faded as well.
GNU Terry Pratchett. GNU Douglas Adams.
Happy Memorial Day.