Sherlock's eyes were wide open now, watching the 'human' John stroke himself and knowing that really, his true form was more than twice that again, just hiding.. waiting to take or be taken.

He licked his lips, then reluctantly moved his eyes from John's cock, to the vibrator in his hand, and then to John's eyes. "I... I thought you wanted to suck me while I use this?" He said holding the vibrator up. It was a swift and hard change of direction, the whims of this half demon were fleeting, apparently.

"So, which is it, Mister Watson? You can't do both.." He teased a bit.

Even as he teased though, he shivered. What if.. what if he really was able to impregnate John? What would that be like? How would look, heavy with child. Could he even look like a human, or would he not be able to shape shift while pregnant? Not that Sherlock would mind of course.