Satisfied with your observations here for now, you exit the room, traipse across the hallway and knock on the opposite door.
"Come in!" A young female voice says from behind the door.
You follow the request and step through the door. You see the puffy ponytail of a teenage girl, hunched over at her desk.
"What is it, Maddie? I'm studying." She says.
From the dismissiveness of the question, you can infer that 'Maddie' is the younger sister. And also, because this girl is facing away from her door, she has assumed that you are Maddie. Before you opened the door, you were planning to make yourself invisible like before, but now you have a better idea.
~You think I am Maddie, no matter what~
You aren't sure if extreme qualifiers like 'no matter what' are necessary, but you want to play a safe ball with particularly unusual commands.
"Seriously, dude, what's up?" The girl asks, tipping her head up and spinning around on the chair to look at you. Going by her posture and expression, Maddie and her older sister appear to have a pretty good relationship, even if the elder one can get a little high-strung about school. Also, going by her not jeering in surprise to see a boy she's never met, your command appears to have worked.
"Nothing much, sis. Could I sit with you if I promise to be quiet?" You ask.
"'Sis'? Has anime corrupted your mind that much already?" She replies.
"Oh me? I'm just fine-desu." You answer with a shrug.
She rolls her eyes and smiles.
"Alright amoto-chan, you can take the chair and you're allowed to interrupt me once per page." She says, pivoting back to her textbook (and mispronouncing 'imouto').
You swoosh your feet around for a few minutes, getting a decent up-close look at her.
~Tell me your name.~ You command, safely assuming this would not come off as natural as a question from her own sister.
"Amber Mateus." She says.
~Tell me the names of your immediate family.~
"My dad Andrew, my mom Alex and my sister Madison."
Okay. Useful information.
~Give yourself a pat on the back.~
You snort as she does so.
You roll a pencil around for a few minutes, waiting until the moment Amber turns a page. When that moment comes, you lean back with a troll-smirk and ask,
"So, any hot guys at school I'm not already aware of?"
She snorts and pays in kind with a troll-grumble.
"Unbearably hot. Hundreds of them. I'm drowning in men. All day, all night. There's five under my bed right now. Thanks for asking, I return now to my regularly scheduled studying." She answers, turning right back to her book.
Amazingly, you seem to fit into Madison's role pretty well, at least for now. You'd expected Amber to be confused by Madison's 'unusual behavior' by now, but nothing you're saying has thus far surprised her. This could obviously be the sapphire ensuring that everything you say be assumed normal, but you've observed the commands only affecting people in exactly the terms provided. IE you made the mom let you into the house, but they were still concerned about you until you made them relax. Well, if you want to figure this out, there's no time like the present to perform a test!
You stand up, plomp your ass right on the desk and forcibly swoop the textbook closed.
"Fuck. You." You say, cocking your head and poking Amber's nose.
She looks back at you with legit terror.
"MADDIE. WHAT...WHA-"
~Forget I just did that~ You hastily return to your chair.
~And uh, return to your studies~
You take a moment to catch your breath. That was fun, and a little scary, and it confirmed that the sapphire is merely convincing Amber that you are Madison, not that anything you do could come off as uncharacteristic of Madison and thus confusing. So wow, okay, it appears Maddie just really does have the same kind of snarky sense of humor and general taste as you do (you already knew at least 3 of the Minecraft channels she was watching...)
Having calmed things down again, you take it easy and wait for another page turn. When the time comes, however, you don't feel any particular question or statement coming to your mind. You don't know either of these people well enough to simulate a conversation as one of them. As you mull this over, there is a knock on the door.
"Come in!" Amber yells.
Madison creaks open the door and shuffles herself inside. Amber looks over at her, then double takes back over to you, then triple-takes back over to Madison, and these 'takes' enter the octuples before she lets out and confused scream.
"UHHHH..." You stammer.
~YOU THINK I'M A SACK OF POTATOES~ You blurt out.
Amber rubs her eyes as Madison cautiously walks towards her.
"Dude is something wrong?" She asks.
Amber looks back and forth a few more times.
"Did you... did you put a bunch of potatoes on your chair and run over to the door...? What did you just do??" She pokes you right in the belly, thinking it's a potato.
"Uhhh..." Amber looks at the chair, but she reacts as though she doesn't see you. "What potatoes?"
Oh that's right, your command that Madison not notice you was still in effect. You strike a duplicate of that command right quick at Amber. She ceases poking you, and instead feels the bottom of the chair (which is actually your legs, and also your crotch a little bit).
"...okay I think I'm a little overloaded right now." Amber says. "I thought you were here in the chair, then I thought there was a thing of potatoes for a second."
"...in that chair?" She looks at her, and then back at your seat. "Are you okay? Have you been up all night?"
"I don't know." She grumbles, rubbing her forehead.
A smile grows on Madison's face.
"Do you need a break from studying or something?"
She steps over to the chair and sits in it. Which, is actually your lap. Oh dear.
"Probably, yeah." Amber replies. She closes her book, and just keeps rubbing her eyes.
Curious as to the extent of the 'do not notice me' command, you wrap your arms around Maddie's belly and pin her in pretty tightly. She 'oof's and tries to get up, but struggles for a second until you let her back up.
"How about you?" Amber asks. "Are you feeling weird too?"
"Yeah..." Maddie turns around and looks at the chair. "I felt like I was stuck to the chair just now..."
"Chair's haunted." Amber replies. "It's waiting for you to fall asleep on it and eat you."
"It'll turn you into fluff and stuff you inside it." Maddie adds. "Its mission is to obtain victims and become as fluffy as possible."
"I'm scared. How will we survive." Amber says, yawning.
You sit in on them shooting the shit for a few more minutes. Madison retires back to her room and Amber goes to the bathroom. You follow her in and are a little surprised to realize that each of them have their own bathroom. Kind of a nice house, this is. Amber yanks her pants down and uses the toilet real quick. As she goes, she kicks her pants and underwear right off her feet; her socks following. You watch as she wipes, stands up and removes her shirt and bra as well. She turns on the bath and crawls in. Fun!