Used to the way Sirius would sometimes decide to change forms, Remus just smiled and muffled a soft laugh at Teddy's surprised expression to find a cold nose in his ear. "He's as much a mutt as a human as he is in this form," he teased, reaching across to get his fingers into Padfoot's fur for a moment. Half the time Remus was sure his friend's animagus form was a dog simply because it was a good excuse for Sirius to be even more tactile than he was naturally.
A trait -- the tactile nature -- Remus was beginning to suspect his son shared. He certainly didn't seem to have inherited Remus' more stand-off nature.
"It's not a dream. No matter how much you might wish it was once everything sinks in," he said softly. "Glittery rainbow fish, I won't rule out, however, as that would not be the strangest thing some of us," he said, shooting the animagus curled up between them a fond look, "have caused to appear in this common room. But, you don't have to do it alone."
He took a deep breath and poked a finger gently into Teddy's arm as he might have done to Sirius or James or Peter. "Now. Pick a snack and pick your questions. We'll see what stories I can tell before you go to sleep in self defence." It wasn't the most helpful offering, under the circumstances, he supposed. But, a night spent telling tales of his school days or his childhood in Wales wasn't a terrible way to get to know his son.