#ihavesecrets

Hello! i am looking for a fix that takes place post war, Harry and Ron are Aurors and there is some sort of mystery afoot and in order to capture the bad guy they set a trap at a ministry Halloween party where when you pass through the entryway it automatically gives you a costume and I think DRARRY were Batman and robin? It was a getting together fix. The only other details I can remember is that Harry sends his patronus to Draco at the party. Thank you so much!