"Your sister," replied Jim.
Rick rolled with laughter and didn't let up until he realized that his friend wasn't joking. "You're serious about this, aren't you?"
"Yeah, I am," said Jim. "I would like to spend the night here to continue translating the book and trying out a few more spells, but my parents have barred me from staying over at your house ever since the last stay resulted in both of us getting arrested. So the only way I can do that is if I already live here."
Rick scratched his head. "But.. my sister? Seriously?"
"Like I said, all you do is say what role you want and you get whatever specific role you said. I don't have to say Rebecca Robertson, Rick's sister; I can just say Rick's sibling then poof I'll become your little brother and Rebecca becomes your best friend."
Rick was more than a little skeptical on how Jim's plan would work out. "Or at least you think so."
Jim sighed. "Look Rick, I'm not leaving you here alone with these translated spells and if I have to be your sister to keep an eye on you then so be it."
"Well," responded Rick, crossing his arms, "If you're going to have that kind of attitude then you might as well become my mom."
"Look it's just an idea," said Jim who got up from the chair. "If you don't want to do it then all I ask of you is to not cast any of these spells without anybody else around in case things go wrong. I'm not saying that because I think you are too stupid or immature to do this by yourself, it's because this could be a little dangerous so let's take a few precautions. Now I'm pretty sure my plan will work and I will become your little brother, the book actually puts extra emphasis on naming the correct role you want to take so you know it's specific."
"Alright," conceded Rick. "We can do the spell, but I have one stipulation."
"What's that?"
"You have to become my sister," said Rick with a dead serious look on his face.
"What?!"
"Yeah, one night with a sister that doesn't get me in trouble with mom constantly or hog the bathroom actually sounds pretty cool when you think about it. Besides, this is one of those things we gotta try out now that we have a magic book. How often can someone say that they were once their best friends sister for a night."
"I doubt that I would be telling anybody other than you." Jim relaxed back into his chair, nodding his head in approval. "Well, at least I'll be around
to keep you out of trouble."