"You leave me with a rather wide selection candidates of among staff, faculty, and students," he grinned. "I suspect that's deliberate."
He smirked, ever so sneaky as he placed a kiss under Severus' ear as he considered the conundrum. "Still at the school, huh? Peter never mentioned you as friend, which leaves Professor Binns, the new Potions professor, and Remus Lupin." He tilted his head and thought some more. "Also, 'still at the school' implies they never left... Moaning Myrtle?" This did demonstrate a pattern in befriending girls from a different house, he supposed.