Rose should take heart. The only reason Ianto knew about Jack's brother was because Jack's brother had tried to kill him. Repeatedly. That had been a very bad day. Otherwise, he was certain that he would have never heard a peep about Jack's family.
Mock indignation ran rampant across Ianto's face. "He tells people about my other things? I'm hoping that those other things are clerical skills or fire arms skills and not .. um. Other things." He stilled, though, at the mention of the Doctor and pursed his lips. It was fairly clear that he didn't much care for the Doctor at the moment, though he tried not to let it show in day to day goings on. "He does. Constantly. Risk his life, that is. It .. destroys him to lose people."