Its artist!Sebastian and he sees Kurt in the Lima Bean and is drawing him. Kurt eventually sees the drawings (by mistake I believe) and one thing leads to another and Sebastian is taking Kurt to his house to paint him nude for a school assignment (can't remember if it was just some hw, or like, a big final project or something). But yeah, Kurt comes to his house a few times and they get to know each other, have lots of sex, etc.
I hope that was enough info, cause I honestly can't remember much more than that. Please help me find this!!!