Sherlock: He couldn't deduce you and asked you to come over to his flat so he could figure out why.

John: You were his patient. He wrote his number on your prescription saying to call him so you two could meet for coffee or something.

Lestrade: You were a witness at a crime. He calmed you down so you could answer questions and then he asked you out.

Moriarty: He just came right out and asked you to go see a new horror movie with him.