I am looking for a one shot, or possibly short story where Kagome is in the future and Inuyasha is trying to get her to mate him. Problem is, he is already mated to both Rin AND Sango. Inuyasha refuses to take no for an answer so Kagome goes to Sesshomaru for advice. He tells her that Inuyasha sees himself as her alpha, so it is his right to decide who she marries/mates. Sesshomaru also tells her that it is probably too late to establish herself as an alpha and she will not get Inuyasha to back off because of this. Kagome decides to return to the past to establish her alpha status so she does not get stuck being a third mate. In the meantime Sesshomaru is also having trouble with the three mates that were basically forced on him in the past and his children that are spoiled brats and want to either have him committed or killed and decides to force Kagome to put a necklace on him so he can travel to the past and stop himself from mating. However, he does not let Kagome activate the spell. Kagome finds the past Inuyasha, but beating him only makes him more interested, so she leaves the village and runs into Sesshomaru fighting his past self. The future Sesshomaru says something that makes her mad and she activates the beads in a way that makes him attack. With the help of past Sesshomaru, she forces the one from the future back through the well. She then tells past Sesshomaru what the future is like with his mates and he decides that mating Kagome will solve his issues, since no demoness will accept being second to a human and Kagome is strong enough to defeat them in a mating challenge.
I have tried looking at all my favorites, in every fanfiction site, and I can't find this. Any help would be appreciated

I believe you are looking for "Instigation" by Demonlordlover, which can be found here: http://www.dokuga.com/spark/story/7713/1.

This story would be rated MA on our site, NO YIMs!!

Enjoy!

~~Wiccan~~