Just a thought I wanted to share. I've seen in a lot of places/fics that people make Cass able to read everybody's body language no matter the species. I don't think she should be able to read the body language of anyone who is not from Earth or at least not any aliens/dimensional beings that did not grow up on Earth. Why would you assume that the whole universe has the same body language?

This is a very good point. Body language is definitely not universal, not even on Earth. Like I imagine even among humans it can’t be easy, because body language is like… not as precise as comics like to play up. Like sure there’s stress, but from what? They’re withdrawn, but why? And then trying to apply that to animals which all have their own body languages - there’s commonalities, yes, but also differences.

And as you said, aliens with different cultural upbringings, different physiologies which favor different ‘tics’. Does a Martian bother with body language at all when they’re born to communicate with others entirely telepathically?