Love the way Ianto lets Jack know that he won't be stereotyped, without being hurtful about it. He'll put with a lot from Jack, but he has limits and I think Jack's starting to understand that.

I also get the impression at the end that Ianto was basically telling Jack that he has no intention of being the sub all the time, he expecyts them to take turns. (Of course that may be me reading more into this than was meant - I still find it fun and cheeky!)