Ianto keeps his arm resting against the small of Jack's back as they begin to walk, keeping him close. Jack's usually the more assertive one in their relationship, so he hadn't really realized how much of a turn on turning the tables like this could be for both of them.
The bedroom door is barely closed before his hands are on Jack's shoulders, not quite shoving him to his knees but close enough. He can still hear the muffled sounds of the party as he unbuttons his trousers and pulls the zipper down, more than ready to get all that fabric separating him from Jack's mouth out of the way.