I really enjoyed this examination of Nimloth and Idril, Astris!  Nimloth's POV is well-drawn.  I would hesitate to call this "AU" because it fits into the world of Tolkien very well for me - say rather "alternative history."  And Idril?  OMG, yes!  I can totally picture her, armored and wielding a sword during the fall of Gondolin!  Even as a backstory referenced by Nimloth,  the imagery of Idril takes on a cinematic quality.

I like how you've highlighted the differences between the women - I come away thinking of Nimloth as a creature of the forest, a doe, and Idril as a lioness.  And yet, in the end, you nicely show how they find common ground.