The white mess that remains of Rachel and yourself is splattered into an over-sized toilet. Samantha continues masturbating until the last bits of you two fill the toilet almost to the brim. She smiles and waits, standing over you two and admiring her handiwork.
She doesn't flush, but that's for a very good reason. As your consciousness floats around, you start having memories that aren't your own. These must be Rachel's, but why would you be seeing them. Rachel seems to be having the same experience as you... or your having the same experience as Erika. Wait. What's going on here?
"Rain, if you don't wake up, I'm going to flush you." Samantha says. You open your eyes in a flash. When did you get a body? More importantly, are you Erika or Rachel. Realizing your underwater you quickly move around, pulling your head up so you can breath. Looking up you can seen the secretary looking down at you smiling. "Oh good, I love it when I don't have to flush such a beautiful girl into the school's sewers."
You look around, wondering where the other girl is. "Where's Rachel.., I mean, Erika... er..." You try gathering your thoughts, but with the memories of both people in your head it makes it hard to filter out the real you.
"Erika and Rachel don't exist, only you do. Be glad I've already given you a name, Rain." The secretary sits down over the toilet, giving you a nice view of her ass, pussy and balls. "Don't try remembering one or the other, because you're essentially both. It can get a little confusing, but you'll figure out you're your own person sooner or later."
"How did you do that to me, um, us... me though?" Wow, she's right, it is confusing.
"If you ever get a cock, you'll find out in class. CliffsNotes version though is that a pred can digest two or more people into a special cum that reforms them into one body when they leave the body. I figure I'd do it for you because your base components wanted to go inside me so badly and I didn't want them to have to wait 9 months before they see the world again, or wait in pred limbo."
"Oh, well... thank you I guess. What now?" you ask after the wall of exposition.
Samantha the secretary laughs. "Well, I'll give you a choice.