Still, as Charlene had said, it didn't take her anywhere near as long to learn what she wanted to know about normal female genitalia as it had for Eva to learn about hers; it couldn't have taken as long as fifteen minutes before Charlene slowly withdrew her hand from between Evas thighs and sat back again. When she did, the two of them simply sat there looking into each others eyes and faces…

Charlene sitting on her feet on the floor while Sis remained on her bed, legs spread wide and revealing the glistening opening between her thighs. It was when Charlene finally stood up a minute later that I saw that the small penis protruding from the dark wedge of her pubic hair had changed. Though it hadn't gotten noticeably longer or thicker, there was no denying that it had gotten stiffer and was protruding nearly horizontally from her pelvis instead of pointing at the floor as it had been before.

Eva slowly brought her legs together and her feet to the floor, then stood up to face Charlene. I could see her look down to the protrusion of Charlenes cock for a few seconds before looking into Charlenes face. Several seconds of quiet were broken when Charlene spoke, her tone of embarrassment obvious as she softly said "I… I'm sorry about that, but it's not something I've ever been able to do anything about. I've asked the specialist that I see about it, and he says it's just a part of who I am, and that nothing he can do will change it: if I get, you know, excited, then the boy part of me will react along with the girl part. I… I've kind of figured out by myself that because my body is different enough to have a penis, there's some little part of me deep down inside that just can't help trying to respond to some things. I mean, I don't do it on purpose, or anything…"