"We're kind of like a point in a function," he says, and Sungmin can't help but to scrunch up his face in confusion. "What makes you say that," he asks. Kyuhyun's smile is fond and soft, and Sungmin feels his heart flip inside his chest at the sight.  He practically holds his breath as the younger says, "Each x-value in a function has a corresponding y-value in said function; just that one y-value. No others. And that one y-value belongs to that one x-value and that one x-value alone."  The brunette pauses, seems to consider something momentarily, and then says, "Lee Sungmin, if I'm an x-value, I want you to be my y-value."