"Probably a good thing," That they hadn't been together every moment. "I'm sure that could get a little tiring, after so long. Having me chattering in your ear about this or that.." He flashed her another smile before glancing back towards his own TARDIS again, then returning his attention to her. "We have a lot of catching up to do, Rose Tyler." The way he said her name, with that Northern accent (lots of planets had a North!) was so different from the way Ten said it. A stark change.
"But right now, I've got to figure out why my TARDIS will only move ten feet at a time." And he needed to sort some things out, especially things dealing with Rose. "Don't get into too much trouble, and don't wander off." That came with a point at her and a more serious look.. but then it turned into a smile. The two Doctors were so different.. one who was willing to leave her.. and one that wasn't. Though Ten had been forced to, Nine had done it willingly, more than once. But he'd always come back. And he always would.