Is it this one?
www.fanfiction.net/s/2128192/1/Metamorphosis
Metamorphosis
InuYasha and Kagome discover that sometimes loving your friends means giving up a little part of yourself, too… Complete
Inuyasha - Rated: M - English - Angst/Romance - Chapters: 82 - Words: 276,777 - Reviews: 2530 - Updated: 2-17-05 - Published: 11-9-04 - Inuyasha & Kagome H. - Complete
This is an Inuyasha/Kagome fic but it does look interesting... I haven't read it but I will be putting it on my to read list!
Rated M no YIMS plz!!