Hi.
Awkward way to start my own post. I have no idea why I'm doing this right now, but I've already started.
My brain has been full of ideas for when Penni ends up finding herself with the Pines family, but I don't want to reveal too much too soon. However, I felt like sharing some information about her encountering humans other than Ford for the first time ever.
She never questioned why she has six fingers because Ford has six fingers. As such, Ford never ended up explaining to her why they both have six fingers. Consequently, she grows up believing that six fingers is just a typical human trait.
Therefore, when she first encounters another human, probably Dipper (I've not got it fully planned out yet but we're progressing forward for now as if it is Dipper), she promptly freaks over this human child missing a finger. It is an extremely stressful situation for him because he then has to try and calm down this girl with weird ears who doesn't fully speak English that he isn't missing a finger. That's just amongst other things as well. Penni's first meeting of new humans is a stressful situation for everybody involved.