John can easily guess what Ianto is thinking, and lifts his good hand to brush down the other man's back soothingly.

"Better for my arm," he points out softly, "means you won't bump into it, and I won't bump it into you."

It will be strictly John's fault if he rolls onto it, not anyone else. The last thing John needs is to damage it further at this point, when it's already sore enough to begin with.