He feels an open summons and lets it grab him -
"I couldn't begin to tell you how to expect the systems to overlap, except that apparently at least as of recently you can summon and unsummon from here. Oh, and when I was gone my clock didn't think I'd been away for too much or too little time, so the worlds are also proceeding in sync, as far as that goes."
"Convenient for calculcating dates," says Tony. "Actually, are our year lengths even the same? I mean, they probably are... Cam, can you make something with date and time calculation specs that Jarvis can look at? Or one of you send him something from your computer, or something?"
"I bet they're the same, we're both from Earths. Maybe there was a restandardization of how long a second is supposed to be at some point but it'll be at least loosely similiar." He calls up a clock app on his computer and holds it up for comparison.
"All measurements seem to correspond," Jarvis reports after examining the clock app's calendar and clock face and watching some seconds tick by. "That's convenient."
"Anyway, unless you want this garage to get awfully more furnished than garages typically are, maybe you should put me in a guest room, how shall I locate such a commodity?"
Cam gives her space right back. Wings folded, tail looped around his leg, arms crossed, standing in a corner.
"There are a multitude of rooms available on the second floor," says Jarvis. "You should both have plenty to choose from."
The elevator lets them off on the second floor, in the middle of a hallway that contains a number of doors on either side; stairs are also visible nearby. "In case you have preferences about the direction of your windows, you are currently facing east."
And Cam picks out a room and starts working on a to-do list with the help of Wikipedia and eating the rest of his sugar glass.
Possibly with the help of a demon. That'll be fun.
Time passes.
In both guest rooms at once, Jarvis announces: "The other human member of the household has arrived. He may want to meet you later today, but first he is discussing some family matters with Tony."