Severus too found the barren hallways of the school to be hauntingly quiet and empty. It seemed wrong, somehow...disturbing. Nearly as much as it was that he had to sleep in the Gryffindor dormitory, along with several others he recognised from his school days, as well as many people he did not; given his age though, it wasn't surprising that he wouldn't recognise as many people as seemed to recognise him. The looks he got told him people knew him, and their reactions told him he wasn't a pleasant person to be around; but a life in which Lily had been killed because of something he did...he couldn't imagine being any other way. So he was rarely in the Tower, expect to make curfew and sleep. Since arriving, he'd spent quite a bit of time in the library or, like Lily, walking through the halls, indulging himself in a little nostalgia.
He was doing just that when he rounded a corner and saw her standing there; his breath caught in his throat at the sight of her so...alive. He was frozen, torn between turning back before she saw him and approaching her to see how she really was. But even if he could have made up his mind, he still couldn't move.