They both watch you while you chat with your "friends". They know that these friends of yours are fake. Nightmer and Dream are trying to restrain themselves so as not to kill in front of you. Nightmare: it annoys me terribly. When will they leave my princess?! Dream: Brother, you wanted to say OUR princess. Nightmare: Shut up Dream. She can hear us. It seems they will leave soon... They were not far away and were whispering to each other and in love with you.