[Ianto likes the exploration, because he likes knowing he's the first man Spike has done most of this with. It feels sweet and special and it's not a race or a competition with Jack or anything like that but at the same time he does want to be the first, does want to have these things be something they explore and experience together and yes they haven't really talked about turning things around and getting Spike on the bottom when it comes to sex but he is sure as hell fucking him before Jack does, he knows that much. But let's not get ahead of ourselves.
Normally he would rely on sound to let Spike know what he's enjoying more, what particular licks and nuzzles are good ones but he's still playing at keeping quiet, at being in public so that isn't an option. He uses his hand instead, tightening his grip on his shoulder almost involuntarily with approval as that tongue moves against him.]