Denial

You pull your hands away. There is a half a moment's delay as she realizes nothing is touching her cock anymore but she is still humping air.
"No," she says, "Don't stop."
You slap her butt and she jerks. For a moment you are worried you may have sent her over the edge but she doesn't quite make it. "I think that's enough," you say.
"No," she cries, and tries to grab her cock to finish herself off, but you grab her wrists and pull them away. She will not be allowed to cum just yet.
You allow enough time for the edge to subside before you let her go. "Alright, that's enough for now. Get dressed. Time to show you where you'll be recharging."
She shakily stands up and, with some difficulty, manages to get her clothes back on, though her cock is still sticking out in front of her, hard as a steel rod.