Hermes froze, and his nude state (as well as his slender form) made his tense muscles stand out very obviously. He didn't let go, he didn't say anything, he barely even breathed.

If you hurt him I'll kill you. was the only coherent thought in his mind, and the ferocity of it scared him, so he closed his eyes and held the Principality tighter, arms around his waist. Hermes' back was used to all sorts of pain. He could handle it; and his body would shield Mr. Fell's.