It had been a while since Fex had last used Ham and he was starting to miss his little companion. Ham was able to be seen by anybody, he didn't have any special skills that allowed him to turn invisible or hide his presence, but he was able to transform.
If the students saw a flying bull-like creature, it would have immediately caused alarm bells to ring, and there would be a hunt for a beast inside of school.
This was why Fex had also kept him hidden as an earring, but right now they were underground, it was unlikely any other students would be down here, and even if they were, it wouldn't be so strange to see a beast flying around on a beast planet. All Fex would have to do was pretend he didn't know his companion and later meet up with him again.
"Finally, finally, I get to spread my wings about!" Ham cheered.
