As Edward’s deterioration grows, the pool grows murky and swamp-like. This symbolizes Edward’s life beginning to end: like the water, which is stagnant and not flowing anymore, Edward is becoming more passive with each passing day. When Edward’s lungs fill with water, William desperately longs for Edward to make a joke, the very thing he has been resisting all this time, showing once again that William finally understands that Edward’s quirks are what make Edward who he is, and they are a very big part of why William loves him.