It still hurts.

'It...' John blinked a few times, trying to remember the reason he was here in the first place. 'It does still hurt, a little.' He looked back at Louise, who only raised her eyebrows once, then back to the doctor.

'Hmmm,' the doctor pondered. 'How much does it hurt, exactly; can you describe it? Does it still feel... good, when your girlfriend touches you?'

He looked at Louise, not wanting to admit the truth in front of her, knowing how much satisfaction she would receive from 'winning' against him. But he was here to be treated, and without correct information, that was going to be difficult.

He closed his eyes and sighed. 'It... does, yes. It still feels good, I mean. When Louise... when she touches me. But the pain's still there, hanging at the back, sort of.'

'Okay,' the doctor replied. John opened his eyes to see Louise, exactly as he'd expected, her expression one of disbelieving victory. She never was one to hold back on gloating. 'If that's the case, I think another test may be in order,' Doctor Harper continued. 'And again, I urge you to only proceed with my suggestion if the both of you are comfortable with it.'

John looked at Louise, unsure of just how much further the two siblings would be able to take this little 'mind game', as she had called it. The thought of her touching him further, her little teenage hands caressing his member after getting it hard in the first place, her hot breath whispering into his ear causing the hairs on his neck to stand, her cute little body pressing against, the curves of her breasts and waist pushing against him...

Fuck, he thought. I'm getting turned on by my little sister.

He quickly looked away before she could notice him checking her out, if she hadn't already, as the doctor continued. 'We should try and get John to orgasm. By watching the process, I may be able to determine some results, and I can test the semen to identify any causes for this pain that might show up there. If, of course, the two of you are okay with it.'

Louise looked at him, apparently finally ready to draw the line judging by her expression. John tried to appear as horrified as his little sister, but the idea of her getting him to climax was too enticing.