I found it!
It's located on ffn and is called Bonds of Slavery
by: Child of the Ancients.
Kagome has been a slave for 9 years and has given up all hope. Then, one day, a handsome inu youkai buys her with the intention of setting her free despite all the problems.
Rated: Fiction M - English - Romance/Fantasy - Kagome H. & Sesshomaru - Chapters: 25 - Words: 71,037 - Reviews: 1,069 - Favs: 575 - Follows: 62 - Updated: 12-10-03 - Published: 09-10-03 - Status: Complete - id: 1514886