William: Sherlock was elated to bump into William while he was out. He had just purchased his gift and was about to head to the Moriarty household. It was good because he was sure Louis would turn him away otherwise. He was able to splurge a little and purchase a nice pocket watch along with a book from a well known astrophysicist he figured William may find interest in.
"Liam!" Sherlock called out to the blond with his usual enthusiasm. "I'm glad I get to see you. I was on my way to your home but here you are in town."
Sherlock felt nervous about his gifts because of his status in comparison to William, but maybe its the thought that counts.
"Anyway, I wished to get you a couple of gifts." He held them up for William to take. "Happy Birthday, Liam. I am glad to have met you."
[Birthday Boy(April 1st)]
"Oh, Mr. Holmes," William stopped his stroll, apparently out on a solo shopping trip. He casually held a box, tucked against himself. He looked the detective over, only for a look of surprise to cross his face.
"Such exquisite choices, detective." He shifted the box slightly so he could take a closer look at the pocket watch and then the book, he smiled when he heard those two words.
"I would ask you how you knew my birthday, but those are relatively easy records to dig up. Thank you, I'll treasure these..."