Blaine is famous, a musician/pop/rockstar of some kind, and Kurt is a fan. Kurt goes to one of Blaine's concerts; either wondering if famous!Blaine is the Blaine who is his soulmate, or just randomly. I think Blaine is signing autographs after the show, he and Kurt meet, and they realize that they are soulmates.
The only other bits I remember are that they don't announce it right away, I think to keep the press and media away from Kurt for awhile. I also think Blaine's manager (or agent? something) plays a role in the fic as well.
I can't remember the title or author at all, though I know it's not petalene's Keeping My Love Safe, which is also soulmate!D/s!Klaine with Dom!Blaine and sub!Kurt.
Any help is appreciated!
FOUND by Amira D: Before We Meet by orchideouss (FYI: Soulmate 'verse, but NOT D/s.)