Are there any fics around Kurt telling Blaine or Blaine finding out about Karofsky sending Kurt Gorilla grams and asking him out?
I found these ones for you. Full disclosure: I haven’t read them. - HKVoyage
A Happy Ending, Finally by beautifulwhatsyourhurry
Kurt's devestated when he finds out that Blaine isn't his secret admirer. However, when Blaine appears at the Valentine's Day Dance, Kurt's spirits are lifted. When Kurt tells Blaine who his secret admirer was, Blaine decides to take matters in his own hands. In a very Blaine-like fashion.
The One in Which Kurt Tells Blaine About Karofsky by KlainebowsandQuirrelmort
SPOILERS 3X13! I am an uncreative titler, so there you have it: Kurt tells Blaine about Karofsky. Cute, funny, silly, jealous!Blaine, Brittanklaine. TUMBLR IS klainebowsandquirrelmort. COMPLETE. ONE-SHOT.
And After by foraworldundeserving
"You can't marry him," the gorilla insisted, letting go of the balloons and reaching up to his mask. "Because I love him." Spoilers for 3x13.
Other Half of My Heart (But Baby, It's a Little Broken) by jakia
Post-ep reaction fic. Hearts spoilers. “But Blaine's not stupid, and Blaine knows your soul better than you do, sometimes.” Kurt suffers a relapse after learning who his secret admirer really is, and gets over it by dominating Blaine in bed. Alternatively, the story of why Blaine and Kurt don’t kiss during Love Shack.
Without Warning by HoneyBooBoo93
Kurt Hummel never suspected David Karofsky to be the one behind all of his Valentine's Day gifts. All along he was certain it was Blaine. After a candid conversation in Breadstix and an incident in the parking lot, Kurt isn't sure how to cope with him anymore.
Note: I’m assuming that this 26k word fic includes Kurt telling Blaine.