John has his arm around Ianto because, his brain says, Ianto is unsteady and high and he needs to stop him falling over. The fact that he also is both of those things doesn't really factor in. He's responsible for Ianto, obviously, and that includes bringing him here and making sure they stick together. Don't get lost. Don't fall over.

Having his arm around him is a logical solution to all these things.

The fact that Ianto is pleasantly warm and steady helps, and John finds the vague mumble of his voice a soothing background noise that he's not really focusing on.

"Yeah," he says absently, then realises he's answering a question and should focus on what the question was. His brain catches up -- mushrooms, right. There's a rule about mushrooms, he thinks? What's the rule? "No," he says, because that's probably the right answer, and he takes a step back now that he can see them -- which means Ianto, who is now leaning into his chest, stumbles back with him. His other arm vaguely comes out around him to stop him falling over, and he frowns down at Ianto. "No mushrooms," he says firmly, just in case his muddled answer had been unclear. Ianto looks different and he finds himself unable to place why, and momentarily confused by it. Does fyrra make you look different if you smoke it? Does he look different? Were Ianto's eyes always this blue? He has no idea.