Sounds like My Savior from sesshou_lover’s oneshot collection Trapped. It’s a whole bunch of MAs.

Hey y’all I don’t remember much from the fic I read a long time ago but I hope someone can remember it.
Sesshomaru and Kagome were in high school and Sesshomaru was being bullied because he hasn’t grown into his body(?)
Sesshomaru is an Inuyoukai.
Sesshomaru is scrawny but at the end of the fic after Kagome helped him he grew into his body. Now every one at the school is fawning over him.
I think Kagome was sleeping with him and maybe Inuyasha was one of the biggest bullies.
That’s really all I remember. Thanks for the help

Sounds like Higher Education by Sunset Miko

www.dokuga.com/fanfiction/story/9383/1?author=78

EDIT BY WICCAN: This story is rated MA, NO YIMs!!

It was My Savior, thank you inali!