It's hard to know what to say, but Ianto's doing much better with the verbal take down of John than Jack ever did. Then again, even with Ianto's insults, he's getting to experience John's everything's-about-sex viewpoint.
"Do you really think I'd want you here after you've been fighting Ianto?" He casts a quick look over to Ianto, "You're actually fine? Because getting it in the balls..." And a glare back to John. "Yeah, well, he's already past betrothed, thanks. Don't get any ideas."