If it were a different kind of shapeshifter, this might not be any use. I wouldn't count on it if you have the same nightmare again.

I'd watch the eyes. They're like an animal's - they reflect glare. Hard to spot if you don't have a video feed, but it's better than nothing.

The ones I know of tend to give themselves away. They're good mimics, but they don't know how to actually be the people they pretend to be. They forget the little details. If you watch for mistakes, you might be able to catch them. You can't count on passwords or shared experiences, though. They can read the memories of the people they mimic.

There aren't any dogs here, are there? Like I said, it's not much.