That's a lot... softer and more earnest than John was prepared for. The playfulness fades from his expression to something hesitant, uncertain. He doesn't like that comparison, the idea that both of them may be drowning, even though he's thought it himself more than once. That he feels like he's treading water here, struggling to stay afloat. It's different including Ianto in that, though. He doesn't want Ianto to drown with him. I'd drown myself long before I let you go under, he thinks, but Ianto doesn't want to hear that. He probably already knows that, even. It's the wrong mood, here.

His hands slip down to brace Ianto's arms and he touches their foreheads together again, trying to steady both of them. Maybe it's at least good that Ianto thinks this way. That he knows they're sinking, even if it stings on some level to know he's given up denying that. What's he even going to prove wrong if he's accepting that they're drowning already? That hardly makes it seem like a good idea. Ianto's not a strong swimmer, in any sense of the word. He's easily overwhelmed, by waves and emotions both.

"Guess we need to work on getting you more swimming lessons," he manages finally, and his fingers squeeze at Ianto's arms gently. He doesn't even know who he's reassuring anymore, Ianto or himself.