Even though it's a joke that John has already made Ianto lets out an abrupt bark of laughter at the thought of it. John's not the only one who's felt the tension rising during this conversation, and it's good to let a little of it out with that.

Sitting forward, he runs his fingers through his hair, taking in a deep breath and letting it out slowly, before he speaks again. Feeling the need to make one final point clear.

"John..." He presses his lips together, keeping his eyes directed down to the floor as he tries again. "There may have been a part of me that compared you to Jack when we first met. And maybe there are pieces of you that are similar. I expect there are pieces of you that have to be. But that's not why..."

He trails off again, before deciding to just go in for the kill. Turning in his seat to look back at the other man, his blue eyes a little guarded and a little uncertain, but oh so honest. "That's not why I-- like you. I just. I need you to know that, yeah?"

They both know he might have used a different word in that sentence. You don't weep over the thought of losing someone you like. But Ianto figures he's pushed the other man enough for one day and anyway, his point is clear enough.