Aliens! The Animal is a person! She doesn't know why that would be at all astonishing at this point but maybe her brain is just very slow to update about certain basic facts. Is a Companion psychologically unlike a human? What is it better at than a human? What do humans trade with it? This is so exciting!
Thellim will very carefully attempt to climb on the Person, praying to the random factors before she tries the 'swing your leg over part' as this operation seems to require momentum which means it cannot be slowed down.