No harm. When he doesn't really react to the touch she draws her hand back, folding it in her lap.

"A couple reasons," she says. "I had been accompanying Sherlock on his cases, and I discovered that I liked what he did. I wound up helping him solve cases pretty much from the start. When my time as his sober companion ended...I stayed."

She takes a breath.

"The other reason was that I had become a sober companion as...a sort of penance."