After Dumbledore enters, Harry sees that “Snape followed him, looking into the Foe-Glass, where his own face was still visible, glaring into the room.” (HP/GoF, 679) Perhaps Snape is checking for magical confirmation of what he knows to be true: his renunciation of Voldemort is genuine. He is so young and new to double agency, at this point, that he still looks for reassurance, for external mirroring of his internal reality, especially since he has so often been disbelieved. As he gets further into his mission, as more lives depend upon him, he will have to learn to avoid or fool magical
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