As far as I remember it's a Blaine/Sebastian fic (possibly multi-chapter), where someone (Cooper???) walks in on Blaine and Sebastian having sex. For some reason Sebastian doesn't want people to know about them, so he freaks out and runs out of there, which in turn upsets Blaine.
I hope someone knows what I'm talking about. I know this is kind of vague, but it has been bugging me for days and I'm getting desperate!