The lips and breath and voice at his throat were making his breath come faster, and his right hand slipped up to Jack's hair, very gently scratching his scalp.
Then the crush of Jack's body against his was enough to stop his breath from coming altogether, immense need coiling in his stomach. He was silent for a few tense seconds, and it seemed that every part of him had halted in expectation of the next second, then the next, then the next. When he released his breath again, it came out in a growl, knowing that Jack was ever an insatiable man in moments like these, refusing to do anything other than tease and rouse until he couldn't physically take more of it. When he began that slow, terrible slide down his body, Ianto tried with arms, then with legs, to halt him, to make him fulfil the silent promises his teeth and tongue were giving. It was futile.
Further and further down Jack went, despite Ianto's protests, despite his verbal moans and his body's silent pleas. He finally resorted to squeezing his thighs against whatever part of Jack slid and tormented between them: his waist, the small of his back, then his torso. But Jack kept moving. Further down he slid until, with the heady anticipation rising in Ianto at seeing where he had stopped, Ianto flexed his fingers, then tightened them again. The entirety of his focus gravitated solely on the deep submergence when Jack took him into his mouth.
"Fuck." It was the only word he could utter over the depth of his groan, and it was an achievement that even that sounded coherent on his damply parted lips. The scarce control he had left went to biting back the urge to buck his hips, and, for the lack of any other body part in gripping distance, Ianto wound his fingers into Jack's hair, hands white-knuckled as he held on, but took care not to handle him too roughly. Not only because Jack's teeth happened to be in an extremely precarious place, but because Ianto would never want to hurt him, in a little way.
He loosened his left hand only to press it over his lover's hairline, pushing his hair back from his forehead. "Jack," he intoned, almost a plea this time.