Still trying to find this fic. I am determined to find it! It is an older story, I don't know what site I read it on. For some reason, I think it may have been in two parts. Inuyasha leaves Kagome behind with Sesshomaru. She begins to run Sesshomaru's house (it was not a castle, and may have not even been in the feudal era). Sess becomes impressed with her sense of duty and how well she takes care of things. Eventually he takes her for his own. Ring any bells?

Did Sesshoumaru end up leaving and his uncle who is not so nice , show up?

Wait a sec.....that sounds familiar! Was it on FF.Net?

Thanks for the tip, Liz, but it's not "One Less Star". I have read that one before though, and just read it again. What a great story. Wonder why the author stopped updating it?

Thanks MontiK, so far I have checked out "Blossom Love", that's not the one, now on to "Family Honor".

Could it be One Less Star? It's on FF.Net

www.fanfiction.net/s/1958248/1/

I think it was on ASS it's the one where Sesshoumaru catches Inuyasha with Kikyo and then has to take Kagome as a sort of surrogate wife thing.. eventually they really mate.

Family Honor

or it could also be

Blossom Love

That has a similar bit where she sort of runs his house and he's impressed. There's also a part where he gives her a sword with 18gems in it for her 18th birthday.

Hope one of those is it

I finally found it!!! It is "Falls on Me" by The Hatter Theory, on FF.Net. I've only just started to read it, but it seems to be as good as I recall. If you are looking for a well-written story to read, give it a try!