Kurt likes a lot of things about Blaine. The way he talks in an extremely eloquent and almost poetic manner. The way his hair is so carefully controlled, but sometimes one strand falls loose and spirals down his forehead. The way he meshes easily into the chaotic mess that is New Directions, almost as if he'd been at McKinley forever. But the thing Kurt likes most about Blaine is his smile.
Yes, it's superficial. He should really focus more on Blaine's kindness or honesty or helpful nature. But, somehow, that's all reflected in the way his lips spread wide and his teeth gleam.
Kurt knows how to differentiate between Blaine's smiles, it's just another aspect of how he understands his boyfriend a whole lot better than he understands himself. Blaine's grins express whatever he's feeling at the moment – even when he's devastated, he keeps up the happy exterior. Most of the time it's for Kurt.
There's the "something great happened so I'm going to jump on the balls of my toes until you notice me and ask me what's up" smile. That one's usually toothy, making his hazel eyes gleam with delight.
There's the "I just had a huge fight with my dad in which he reminded me of how much of a fuck-up I am but let's not talk about it right now because I don't want to burden you" smile. It never reaches his eyes, no matter how hard he tries to make it seem genuine. Kurt sometimes thinks back on these occasions with bitterness; Blaine's not the only one who can be a prince charming.
Then there's the famous "I'm on stage right now and I feel invincible" grin. It's one of Kurt's favorites. The sheer euphoria Blaine can convey in one simple expression speaks volumes about how open and warm he is and it reminds Kurt of all the ways he loves the crazy midget.
But there's one special smile that negates the rest. Kurt likes to call it his smile. It's the one Blaine wears when Kurt says something about how he can't stand another second looking at Rachel's reindeer sweater or how he's going to pummel Finn for slipping to Burt what exactly Kurt and Blaine were doing in the back of the Navigator or how he simply cannot contain his rage at the current breakup or makeup that happened today at Glee because seriously these kid's hormones are out of control. Blaine surprises him with his smile at the most random times, ranging from when he's wearing his bitch face and whining about the latest dramas to when he's consoling Santana about her failed romantic endeavors in secret because he really does harbor a soft spot for that satanic girl.
Blaine gives Kurt his smile every time he presses his slightly chapped lips to Kurt's perfectly moisturized ones, creating that feeling of utter happiness and safety and warmth that Kurt adores.
They're sitting on the edge of Kurt's bed, trying to get some homework done because really, it's two weeks until exams and even geniuses like Blaine need to study. Kurt sticks his tongue out of the side of his mouth, focusing hard on a Calculus problem that's taken him over ten minutes, frustrated because it should've only taken five. He glances up, needing a distraction, and hazel eyes meet blue. Blaine's giving him his special grin and Kurt's heart swoops involuntarily.
"I love your smile."
Kurt blurts it out without thinking and isn't really all that bothered by his own sudden declaration, because it's definitely true. If it's possible, Blaine grins wider, albeit a tad redder in the cheeks.
"I smile every time I think about how much I love you. It happens a lot."
Kurt thinks that's about the corniest thing he's ever heard and surprises himself by deciding he doesn't care, not in the slightest. So he rolls his eyes, throws his textbook off his lap, and pulls Blaine in by the collar, twirling his fingers in the curls on Blaine's head as their mouths meet.
Yeah, they're not getting much schoolwork done today.