Aang rarely slept these days. So the fact that he was up shouldn't be much a surprise to anyone. When he slept his nightmares were vivid and painful. All he felt from them was bitter and pride hurt. So he made it routine instead around this time of night to visit Appa in the gardens. The Giant Sky Bison had been there before, so everyone was probably used to it by now anyway.
Aang was practicing waterbending when Alessa came out. Trying to remember everything Katara had taught him. In the garden there was a small pond, so at least the water was easy to access. Aang moved his hands in a flowing motion like the currents themselves in the light of the full moon and created small waves. Drawing power from the light to make them larger and larger. Then, he heard a voice and his concentration broke. So did the waves on the surface of the water. Causing the pond to be disrupted. "Sorry?" He looked confused. Wondering what the girl was talking about, and to who "...I didn't realize anyone else was awake. "