If Jack had had any idea that knowing, irrevocably, that he was being faithful would give Ianto such confidence, he might well have succumbed to the idea of his own accord a long time ago. The air of dominance in the way Ianto deftly guides him to the mistletoe and then proceeds to kiss the living daylights out of him has the arousal that’s been simmering underneath everything spiking sharply and he gasps into the kiss, Ianto’s possessiveness sparking other, more basic, instincts. If he’d thought Ianto’s new-found confidence extended far enough, he’d have been dropping to his knees around about now.
As it is, he just goes very pliant in Ianto’s arms, and when the kiss finally comes to an end, he laughs softly, eyes shining as he shakes his head in wonder at how far they’ve come. “You have no idea how far I would crawl for you when you’re like this, do you?” he murmurs, marvelling at it all.