Vanitas hadn't planned on locking eyes with anyone, let alone the redhead who hung around the one called Roxas, but it presented an opportunity. He wasn't ready to speak to Roxas yet, because Vanitas didn't want to lay all of his own cards out on the table to get the answers he wanted, but engaging one of Roxas' friends in conversation might work. Unfortunately, violence was strictly prohibited at Yellow Brick: not being able to use force cramped his style quite a bit.
Although his expression was far from warm (Vanitas wouldn't know how to look warm even if he tried his best), the smile that spread on his face was inviting - in a challenging sort of way. A motion of his head toward the doors closest to him further indicated he'd like to talk, but not in the crowded cafeteria.
Without bothering to see if he would be followed, Vanitas turned and left the room. He was waiting in the hall outside of the cafeteria door, leaning against the wall beside it.