He'd said it as a tease, of course. Testing Spock's patience as always, having little too much fun with flighty comments and a show of nonchalance that he doesn't feel right now, not in the least.

He knows Spock can make this difficult for him. He can turn this into torture all too easily, and not the kind of torture that Jim would enjoy. He can and will use that calm and patience of his to make Jim really suffer, really wait for it, and the more Jim pushes at his limits, the more likely that is to happen.

So, maybe if only briefly, Jim's expression sobers up, turning just a hint more serious. His smile fades and his dark gaze fixes on Spock's, not even a breath of a complaint when Spock undoes the knots and the rope eases around his wrists. His arms fall to his sides.

Licking his lips, he swallows dryly, searching for the words before answering.

"Because... I love you. Because I spend every minute of every hour of every day thinking about you. About making you smile, making you as happy as you make me."

He leans in just barely, lips brushing across Spock's knee.

"T'hy'la," His voice is warm and soft, and he purrs a little, closing his eyes as he nuzzles his knee, cheek brushing softly against it. "You're the only one that can make me feel good. The only one. Please..."