"Good to know you are capable of calling me "sire" without all the sarcasm," Arthur commented.
"Why's it good? When am I going to need to?" Merlin mumbled in reply, still sleepy.
"Well…you might need to speak to some real, modern day royalty sometime"
"And you think an "I want to shag your brains out" tone is better than a sarcastic one, do you?"
Arthur poked him in the ribs. "No need to be crude, Merlin," he said in mock disapproval.
"Sorry," Merlin replied, and for a moment Arthur thought that Merlin had actually allowed him to win this little "argument". His hopes were soon crushed though, when Merlin came back with: "I was pleasantly surprised too, you know"
"Oh?" Arthur queried, suspecting the remark wasn't as nice as it seemed.
"Yes. Hadn't realised you knew the word "please""
Arthur poked him again, a little less gently, and Merlin grinned at him. Arthur found his face automatically mimicking the movement. Merlin really did have the most infectious smile he had ever come across.