"No..." Steven says softly from behind him. "They're not."

While Papyrus is looking for answers, Steven already seems to have determined his own. Though Papyrus would be used to seeing Steven in his faerie form, it seems that he has suddenly taken on the appearance of looking like a normal human child, with no sign of his fae traits at all.

It's all an illusion, of course. But the sight of everything going on around them is enough that he already knows he shouldn't be seen.