I was actually a few years too young when OotP to really be affected by Sirius' death; at the time I didn't see his importance as a character, and while I knew that R/S was a popular pairing, I wasn't interested, because "old guys." They were over thirty! Way too old. I vividly remember the anguish on my friends page from his death, though, and I think if I were part of that fandom now, in my late 20s with so much more life behind me, that it would hit me in the same way as them.

Close reading in the current fandom climate is, first, just a great way to engage with people over topics that have much lower stakes than our current IRL topics of conversation (politics). Second, as a writer, I believe close reading lets me know what people tend to look for (or trained to look for) in character interactions and to tailor scenes that are much more subtle on the surface, but to the astute reader can scream "THEY'RE GONNA FUCK."