Usually, Marshall has the warning of at least a few days before his changes by the fact that he normally follows right on the coattails of one of his best friends on the island, Gaius.
Unfortunately, this time, it comes without immediate warning. Marshall and Gaius are injected on the same day, and in fact, Marshall's changes begin about an hour before Gaius's.
As if things hadn't been bad enough for the penguin-man, this last change brings more features that would be wonderful in a frigid environment. While he had already been packing on more pudge, he begins to become even more rotund with this last transformation. His innards twist and twine as his center of balance lowers and his torso extends to halfway down the length of his thighs.
But that's not the worst of it. His flipper-hands become even more like flippers. While flexible, where he could perhaps distinguish individual fingers in the mitten-like covering, they become smooth, gradiation between the bones and digits smoothing over entirely, his thumbs even shirking away...
The remains of a distinguishable nose fade into his face while his bill becomes thicker and stronger, leaving him with a face almost entirely penguin except for his still shining, human green eyes.