Ehehehe. That's not stalking; it's wiggling on very stubby legs.
[Oh. He'd be able to tell just by the arch of the rock where it was thrown from, but Ciel's temporary seat being there so nice and visible makes it even more obvious.]
Goodness, but we do need to work on your aim. [Naturally he assumes it was meant to hit him. As you do when dealing with precious innocent children. Sebastian immediately turns tail wagging and walks over. He slows down as he nears the rock, kneels carefully - not wanting to accidentally hurt Ciel again - and holds out his hand.]
I'm deeply sorry about all this inconvenience. [Now come here and let's not get separated again until they can figure out this invisibility problem. This time there will be no dropping Ciel. Calm demeanour aside, he really isn't happy about this at all.]