The Poor Doctor had had a very trying day, understandably. So when Rose began to posture up and become her normal, beautiful, defiant self, he couldn't help his immediate resistance to her want of freedom. Nine had a way of getting irrationally angry, for no good reason. He also had a way of getting irrationally happy, for no good reason. Funny, how that worked. But all the same, he pinned those impossibly blue eyes onto Rose and was opening his mouth to refute everything she'd said..
But then he stopped.
Perhaps it'd be better for her, to believe she had something to protect. She seemed to work her best under pressure, knowing others were on the line. Knowing friends were on the line. He'd witnessed that first hand. So, after a few seconds, he smiled again and nodded.
"Alright, Rose Tyler, you had better keep your eye on him, then, if you end up with him. And that John Smith. Worthless, he is." And with that, he was turning to grab up a few things he'd collected up the previous day. He needed to get to the carnival. Then the gas station. He had things to dismantle.