[ If he wasn't this drunk and unhappy, he might not appreciate it for what it is. If he hadn't been on the other side of this when Jack disappeared, this would be a moment of apprehensive tensing and wanting no part of this but they're so past that and so he reciprocates, curling an arm around Ianto's back.
We can't be too chummy, though. Of course not. Men can't have squishy emotions. ]
I'm not going to make out with you, if that's what you think.