Shinji briefly watched Dorian's attention stray between himself and the balloons, before once again look around at the other guests. Niflheim would never hold something like this. He wasn't quite sure what he thought of the music; he didn't know a single song. He wondered where most of it was from.
At the question, Shinji returned his attention back to Dorian. Grinning at him, he shook his head. "Helium. It's a gas which is lighter than air, so it rises. Because those balloons are filled with helium, they'll rise too. The ones that aren't floating have just got air in them". He hoped that was all Dorian might like to know about helium (other than it made your voice high pitched if you inhaled it), since his grades in science were, quite frankly, appalling and that was more or less all he knew with regards to the properties of helium.