"Angus!" Joan exclaims, then shakes her head, amused. "No, you wouldn't be Angus." She turns to face him as she explains. "Sherlock has this phrenology bust he named Angus. He used to explain things to it when he needed to talk through his thoughts on a case. At one point, before I became a detective, he said I was his new Angus, that he would talk at me and I should just be silent." She rolls her eyes. "You can imagine what I told him he could do with that idea. But it actually is really helpful to talk through a case with someone who isn't part of the investigation, especially if you're stuck. It forces you to organize your thoughts, and the person you're talking to can sometimes notice things you've missed."