Nate was feeling a little curious... about a number of things... Like maybe exploring a female form, having sex, and maybe seeing how the other half lived... and maybe messing with the other half. As it just so happened his little sister of 14 was at a sleepover with 3 of her friends in the rich neighborhood... Nate would feel a little icky just being in his sister's body so when he swapped he just decided to swap the age, gender, position, social standing, etc to be equivalent to his little sister but just not her actual body...
After a split second of confusion as reality settled with Natalie the otter tailed girl was sitting on a couch watching a movie with her friends Kara, Zoe, and the rich girl hosting the event Vanessa. Natalie excused herself to the little girl's room, and looked at herself in the mirror... Then she checked her tail confirming that it was in fact her Natalie and not her older brother's original body. She checked her shirt and found a bra holding her breasts that had gone through a growth spurt. Then patted her groin and figured it had all worked and even had the remote through the switch. So now she just waited a bit of time, flushed, cleaned her hands, and then went back out and sat back on the couch as she tried to figure out how best to go about messing with the other fellow girls.