Hi! Self-promotion begins here.
I'm going in this direction in my fic, 'A Twist in the Myth.' In the beginning, InuYasha's pack (InuYasha, Kagome, Miroku, Sango, Shippo, Shizu, Shiori, and Kirara) and Sesshomaru's pack (Sesshomaru, Rin, Jaken, and Ah-Un) are travelling separately, but in parallel as they hunt Naraku. Events cause the separate packs to merge into one, through a super-sexy orgy in a den-like cave (Chapters 26 through 30, 'Union of the Packs' pt. 1 through 5). Eventually, they emerge from the cave as a single pack under InuYasha's leadership.
Sesshomaru/Kagome is found in Chapter 30 (Union of the Packs - pt. 5), Chapter 36 (Between the Brothers - pt. 1), Chapter 37 (Between the Brothers - pt. 2), and Chapter 38 (Between the Brothers, pt. 3), with more to come.
Later, I'll have the united pack serve as the nucleus around which a new feudal Japanese province is founded, and I'll thrust InuYasha into the pack politics of Koga's wolf demon tribe.
Story is loaded with extremely-explicit sex scenes and explicit violence, so it's definitely rated MA. No YIMs! Read it
here! I hope you enjoy it!