John/Rose
No, you weren't lying. Actually, it's going to be difficult to pick just one. I have a feeling even if we choose a Chihuahua, Sherlock would train her up for detective work.
When can my sister and I come to see them?
Oh, this is supposed to be a surprise, and Sherlock notices details, all the way down to dog hair on a person's clothes. So, this is asking a big favor, but do you deliver?