Well: 1- In First Class, Hank originally had ape-like feet but looked overall human. After he took the serum, he turned into the feline Beast form. Were his feet always gigantic, proportionally speaking? In truth, I only remember his hands being slightly bigger, but I could be wrong on this. Could you check this out? 2- How do you think the transition between the Feline and the Ape form happened? I guess it was an unwanted counter-effect of the new serum he started to take inbetween First Class and Days of Future Past. 3- Is it me, or in Dark Phoenix Hank can switch from his human-looking form to Beast form without getting "angry"? New, refined form of his serum?