| Quote #7
When the eyes of Prince Prospero fell upon this spectral image (which with a slow and solemn movement, as if more fully to sustain its role, stalked to and fro among the waltzers) he was seen to be convulsed, in the first moment with a strong shudder either of terror or distaste. (10)
Prospero's own first reaction is more ambiguous than that of the rest of the revelers. It could be disgust, but it could also be terror. It's certainly clear that he's surprised and unnerved by the Red Death masquerader.
| Quote #8
But from a certain nameless awe with which the mad assumptions of the mummer had inspired the whole party, there were found none who put forth hand to seize him; so that, unimpeded, he passed within a yard of the Prince's person; and, while the vast assembly, as if with one impulse, shrank from the centres of the rooms to the walls, he made his way uninterruptedly, but with the same solemn and measured step… (13)
The crowd is too afraid of "the mummer" to obey Prince Prospero's order. They all shrink away from it. Prospero himself is no exception.
| Quote #9
It was then, however, that the Prince Prospero, maddening with rage and the shame of his own momentary cowardice, rushed hurriedly through the six chambers, while none followed him on account of a deadly terror that had seized upon all. (13)
Prospero's rage gives him courage. He is the first and only one of the masqueraders to overcome his fear and take action. Everyone else is in the grips of a "deadly terror." The fear continues to rise.