I loved the way you portray their relationship. They were really in character and I commend your skills for that. I think that there are only few things that you need to improve. First is that writing in blocks of paragraph while having two-three people converse at the same time makes your readers confused. It would appear a lot more cleaner, organized and reader-friendly if you would separate the dialogues of different people. Like for an example, when Kagura says 

"Leave me alone" (enter description of her emotions here)

--you put a space in between and place the other dialog below

 "Submit, Kagura" (Description of Ses/emotions)

Second, Sesshomaru is not really fond of words so he basically doesn't say a lot of things when he talks. When he is asked he only replies "hmm" and most of the time he only stares at the person and nothing else. I would suggest that you don't make Ses too much of a chatty person.

Third and the last, I think that you did a good job in describing their emotions but as a reader, I find it a great deal for an author to describe his characters' emotionsemotionally haha. 

All in all, I love your story even to the point of having me registered here in this site just to submit a review! hehe I see that it has been years since you last updated. I hope that somehow you'd find the time to finish this! 

Au Revoir, Ceecee!