I had this saved on FF.net, but I'm afraid a lot of my info there tends to wind up missing/bumped off/etc.

If I remember correctly, this is a fic from anywhere around 2002-2007 and was a rather long trilogy. Kagome wound up with Sesshoumaru but had to create a subduing necklace for him to sneak their way into a village. When she subdued him, his tail/mokomoko would curl into a question mark behind him. The need for it was so she could convince the village that was holding Rin that Sesshoumaru was her slave. By the third part of the trilogy, Kagome had developed further powers and wings.

Forgive my memory, but I want to say the author's name was Amy...

Any help would be greatly appreciated!

This sounds like the Unexpected Allies trilogy by Striking Falcon (rated R on Spark).

Crud.... just read this the other day. Rin was kidnapped and taken to this dark miko village (eventually to be sacrificed worth other children), Sesshoumaru takes Kagome to this slave trader he has and together they learn how Sess can be a 'proper' slave to get past the barrier that surrounds the village and fool the inhabitants. Her disguise was as a blonde. And he had Brown hair. Kagome gets wings. Can fly and protect with them. She gets kidnapped or from under Inuyasha's nose afterwards and there is a big war.... let me check around my favs and see if I can find the name.

RebaJean, thank you! I knew it was one of the authors I would kick myself for forgetting! Thank you again!