Waiting on the Wise, by rhymer23
This is set in the month the Boromir spent in Rivendell between the Council of Elrond and the departrure of the Fellowship. It's a very popular period to write because you have so many characters that don't usually interact in close proximity to each other, and because it's set in a more or less settled residence, meaning if you don't know the first thing about cooking over a campfire or caring for horses, that's not going to be a problem. You can lock Boromir and Gimli (or Legolas and Arwen, or Merry and Gildor, or... you get the idea) in a room together and just see what happens. The period can sometimes feel a little overdone, at times. I've certainly written my share of stories like that.
So if I say something along the lines of "Boromir gets cabin fever, goes exploring, and must save characters Merry and Pippin from a charming mini-adventure," that might sound a bit familiar. And perhaps it is. What's not familiar, at least in my reading, is the utter maturity with which Merry and Pippin are portrayed - these may look like children, but they most certainly are not. Boromir's cabin fever, the reasoning behind it and the way he responds are spot-on as well, as are the various causes of angsting I could go into but I should probably leave something for Rhymer's story itself to give away.
I'd say reading this felt like falling into canon, except that's not quite it. It's better than that. It's falling into canon as it would have been if Tolkien gave us fully fleshed-out characters like I'd expect from a contemporary novel. But the world, the realities and inner logic and all that, is so thoroughly Tolkienish it felt like coming home after years away.
Let's just say this is the first story I've read by this author, and it put her on the short list of authors I will make the time to read the next time I see her fic on my LJ page.
ETA: As dreamflower02, Rhymer has several other stories at her MPTT page. Check it out.