"Not a lot," he admits, but he relaxes again. He has no problem with the idea of mucked-up timelines, at least. "But it makes more sense than the date rape idea. You don't look like a rapist." His smirk suggests that he's glad Ianto's not a rapist.
His brain finally catches up with the rest of it. "So... You know me - an older version of me - and we're in prison together?" He glances round. "Have to say, in this case I'll take prison over where I was before any day!"