M, complete, 15715 words (link goes to AO3)
Erestor/Glorfindel, Elrond, Lindir, OMC
SA 1699: Imladris is under siege, and just now, Lord Elrond decides that the captain of his guards should take Glorfindel under his wings. Erestor is not amused; he doubts Glorfindel's claim that he is the re-embodied Balrog-slayer. Likewise, Glorfindel has no time for the lout from Eregion. But when they set out on a mission, truth will out.
"If he were to lift a sword, he would probably topple over! Glorfindel of Gondolin, if I remember correctly, was tall, straight and had hair of shining gold. He was fair and full of joy. That one? Valar, he weighs half of me, and that only if he is dripping wet! And full of joy? I met lemons with more zest!"
Notes: Someone, somewhere asked for reversed Erestor/Glorfindel dynamics. For the life of me I cannot remember who it was, for I have the memory of a goldfish, but my gratitude to this person for releasing this plot bunny. In the unlikely event that you should come across this tale, please yell.
Also, I have once again been tweaking the timeline. Glorfindel returned from the Halls of Mandos between SA 1200 and SA 1600, depending on who you argue with. I have always conveniently ignored this bit of canon.