There's a sharp look at the other man, and a coloring of mild surprise, although he's not sure why. Not that Ianto had talked it over with Owen, but maybe that Owen had advised him to tell Jack. It's not a move he would have entirely expected. He drops the banter- it's meaningless anyway, void- and moves forward with the true subject instead. After a second drink.

"Is that what it's called when you decide to save someone's life?" To save the life of the person you love? The question isn't entirely without heat, but it's not directed at Owen himself but at- fuck if he knows who it's directed at. He's angry- at Ianto, at himself, at the world at large, and that anger simmers over a boil of another emotion he's determined to ignore. Ianto hasn't died yet, not in Jack's timeline, and he's not going to let him die. There's no need for any other emotion. "Because I thought that was a pretty logical reaction."