Ianto chokes a bit on his tea at that first line, typical though it might be because its not the sort of thing he usually hears for Jack. Its the combination of the Mr. Jones bit and the taking advantage idea. He coughs a few times and clears his throat, regaining a bit of his usual composure.
"Well I have got that stopwatch now," He reminds him. He can always think of new stopwatch activities. More seriously he elaborates, "I want to make sure you know I don't want to do anything that physically hurts or injures you. I've watched you die too many times to be able find anything arousing in that sort of a situation. I think I'd just see a body." It's a dark turn for the conversation to take, and he knows it, but this is his only ground rule and he wants to set it before they go any further with this.