For a second, Erik stops dead in his tracks, confronted by a face from his distant, almost-forgotten past. Then his vision clears and he makes himself look at the woman as she is, with his own eyes, not those of his memory.
Then, she smiles, and it's like the smile of a serpent. Something in Magneto shudders, even as he finds himself intrigued by this puzzle.
"You do not know me? That is...unusual, in these halls. My name is Erik Lensherr...though I'm also called 'Magneto.' And, on occasion, the Devil himself."
He chuckles, slightly self-deprecatingly.
"Though of late, this place has become home to others potentially far more deserving of that title than I. But never mind that. What are you called, child?"
He looks around with a slightly bemused expression.
"And however did you get down here without any form of security clearance?"
The question is more one of curiosity than anything else...a statement of "I wonder," rather than "I demand." There are a multitude of ways to bypass the security systems at Xavier's...high-end shapeshifting, phasing, and technopathy are but a few of the more subtle ones. Erik is mostly curious about the specific 'how.'