After all this time, Jack knows very well what will turn Ianto on (just as much as it turns him on), but he's still unprepared for the level of need in Ianto's voice as he answers, and it sends a surge of want through him in response.
"I'm glad," he says breathily, because while finding Ianto already loose and open from Spike would be pretty hot (and may well be when they get down to in their actual - or, well, slightly less virtual - bodies), he wants this time, here, in the Hub to be about them.
He squeezes out lube, warms it up between his fingers, and then slips one of them down between Ianto's cheeks - doing it by feel so he can stay leaning over him, breath on his back, his own elbow on the desk beside Ianto's, his still-clothes cock brushing against Ianto's hip. He plays for a moment with just sliding his finger up and down Ianto's crack; then impatience gets the better of him and he presses on inwards, gasping as his finger is sucked in by hot, tight, silky flesh.