You slowly grin. "Kristen, I like your thinking." You say, reaching one of your slender arms past her hermaphroditic form. "First you gotta let me try one of those things, though!" you say with a wink, extracting a purple pill from the receptacle.
Kristen beams at you, a look tinged with directionless lust. "Little... uh, sis- I just knew you'd agree! I'll catch you after you black out, okay?"
"Okay, sis."
.........
You open your eyes blearily, taking a moment to try and remember what you're doing on the floor. You blink a few times, clearing your vision, and notice your sister kneeling next to you. You suddenly become aware that you have a rather visible erection, and blush heavily.
"Bro? You're awake?" Kristen says. You feel really uncomfortable, but you manage a nod. "Good, well, now we can see how consistent the purple pills are."
Suddenly lucid, you realize you're rather more grateful for the feeling in your nethers. You remember being a girl before losing consciousness. You also feel a little less self conscious after remembering the aftermath of Kristen's purple pill.
Your thoughts are interrupted by your sister placing a hand on your... breast? "They're a little bit smaller than mine, but you /are/ younger than me, so that's to be expected." She grins. "We came out just about the same, little sibling!"
Being already kinda familiar with the trappings of a female body, you're not as shocked as you thought you should be. The merging of the two, however, fills you with a strange yet delectable melange of curiosity, alienation, and superiority.
You stand and hug your sister, who happens to be the only person in the world who shares your odd form. "Alright, sis. Let's...