Sherlock. His last vow. I don't think it was for his brother. If anything, he wants to go against his brother, although yes, Mycroft is an odd name also. But Sherlock is different and his own person. He could never be a William or Scott because that's not who he is and what he represents. Also, makes me wonder where the name came from and who originally named him that.
Sherlock, your Benedict is showing. <--I practically melted when he apologetically said "I do. I just wanted you to speak quickly." HIS EYES! And then I burst out laughing when he said "Ms. Mackenzie will need to breathe into a bag now." XD