The hands in his hair and on his neck help, they soothe him and help him narrow his focus to what he's doing. He hears the edge to Ianto's tone, though, and there's something gratifying about how he's barely had to put effort in to get him so aroused. John lifts his eyes to study his expression a moment, drinking in the flush on Ianto's cheeks and the dilation of his eyes as he slowly works his shaft with one hand. He's gorgeous like this, and it's difficult to believe Ianto really thinks nobody would want him when everything about him is perfect to John. Thermal layering included.

Then he's squaring himself up, taking Ianto into his mouth and working the base of his shaft with firm, insistent motions.