Things Everyone at the Party Might Notice
1. After Ares the God of War arrives, he laughs at John being cheeky and the laugh echoes around the flat. This might just be considered part of the sound from the stereo, or not. As you wish -- whether or not you wish to use it in part of your own sub-threads.
2. Harry becomes very upset seeing his mum with Severus. http://asylums.insanejournal.com/writeaway/7066.html?thread=146074#t146074 Most likely only those nearest might hear or see this since it's not exactly a quiet party. Sorry, I had Jonesy in the thread and forgot about him. So he can talk to Harry maybe or Luna? Or both?
3....
Does anyone have anything else which could be noticed party-wide?