"Church is easy," The Doctor said, taking the muffin Amy offered him. "It's off-limits, something creepy's in there--yes, definitely where we want to go next, I think." He smiled at her, peeling the paper wrapper free of the bottom half.
He brightened considerably at the sight of Sam, whom he grinned and nodded at with a bubbling enthusiasm. They were off to investigate people in the pizza, and The Doctor was busy grinning and nodding like a giant idiot. Which, to be fair, he sort of was. (He was a bit too smart to qualify for idiot, but giant and childlike were practically synonymous with The Doctor at this point.)
And the grin only got bigger still when Gretel arrived. And said exactly two words, which was more than enough for The Doctor. People who didn't talk a lot were actually quite decent companions for him; their silence left plenty of room for his babbling.
It wasn't until his own self got there that The Doctor was ready to get things well underway. "Alright, everyone!" he said. "If I can have your attention for a moment--we're going to be investigating the pizzeria. I've heard from the employees that the meat is suspect and we absolutely must be certain we're not eating humans." He paused. "You know, that being bad for the general order of things and you lot not being people who generally feed on each other."
He pointed a finger around at all four of the others, landing last on himself. And would that ever get old? Probably not. "We'll probably have to break off into two teams when we get to the pizza shop, but until we arrive, I'd love to hear more about the two of you I don't know, and in return, we'll all tell you about us. I'm also The Doctor, but I'm the floppy-haired bow-tie Doctor, and he's the pinstripe Chuck Taylor trainers Doctor." He pointed at his eyebrows. "And if you're really uncertain, he's the one with eyebrows."
Grinning like a maniac, he swept his arm to the side. "Well then! Shall we get started on our pizza adventure?"