He caught her scent before he spotted her, stopped short and smiled to himself as he tilted his head upwards and gave the air another experimental sniff.

"I can smell you, sweetheart," he called out into the dim corridor, singing and kicking in doors now forgotten as he shifted his attention and slowly began to move in her direction, cautious and deliberate. "And I can hear you breathing, too. Don't be shy. Come on out and say hello."

Or he'll come to find you himself.