A Cloak of Magic by LadyBrooke

Chapter 1

She was once an elf, before Sauron invaded their lands and took her, twisted her, gave her the knowledge to transform into a bat, and gave her a cloak to use when she carried messages.

Now she is Thuringwethil, and she is one of his messengers, the only one who knows the lands well enough to avoid the elves that would slay them, the only one who can walk past them with her cloak pulled on and pass as one of them. She thinks sometimes that means she might still be one of them, and this is not her final fate, serving a master that she loathes beyond anything, who has taken her from her family.

Her cloak is beautiful, it gives her the strength to do what she must, and it is infused with Sauron’s magic.

And she throws it off in the midst of battle, near enough that Lúthien will see it and take it, and lets them think she is slain.

Then she flees east, away from all of this.

She doesn’t look back to where she knows her family still lives, because she is not sure if she still does and she will not curse them. 

Chapter End Notes

It's not really necessary to know to understand this fic, but in case anyone was wondering if I had a specific person in mind for who she was before becoming a vampire: Yes. My headcanon for years now has been that she was Orodreth's wife, captured in the fall of Minas Tirith.