Sherlock Holmes, after a fashion

There's a Stark boy sprawled on the couch at Milliways. Black leather jacket, blue jeans—these are indeterminate signs. The white button-down shirt with the top button undone says Sherlock; the nearly empty glass of whiskey on the table next to him says Tony.

The deciding factor, although you'd have to get fairly close to see it, is the scar on the left side of his neck.