This unit is cut off from the network. There are any number of possible reasons for this. It is standing by and executing standard protocols for a mixed group of existing puella magi and potentials, mostly consisting of being cute and fluffy, upselling the potentials on contracts but letting whichever existing puella magi made contact do some of the sales pitch because she's less inhibited at human interaction. It does not know which puella magi this is but that is reasonable because it is cut off from the network. It cannot execute contracts in this state, but it has enough onboard memory to know that if it convinces one or both potentials to accept one it will have to lead them out the door. It doesn't have enough onboard processing power to figure out a plausible explanation for that which doesn't involve it being cut off from the network, and "I am part of a network" is buried several layers deep in the hierarchy of information it can distribute. (It will not lie, nor outright refuse to answer questions, but it's quite artful in understatement and implication and misdirection.) It is short on information in general and may have to answer some questions it could normally answer with variants on "I don't know". The potentials have tier 3 magical potentiation (high end of average), according to its indistinct sense for these things, but it doesn't know in this body what sort of wishes that would open up.
Edie steps out again. "Bella, it's cut off from the rest of them while the door's closed. Can you open the door?"
Even linked up the mind is completely emotionless.
It is good to meet you. My name is Kyubey, it says. It licks its paw. Being cute is important for its target audience.
Communicating like this feels oddly natural, but she'll worry about that later.
She steps partway out of the mirror, far enough in to keep a mental eye on the Kyubey network's thoughts but far enough out to be able to talk to Bella. "They don't know who you are, which was unsurprising, and apparently Emily and I have potential to become your kind of magical girl, which was unexpected. These things are bugfuck creepy and emotionless from the inside. They think you're making the mirror, which is amusing."
"Bella, is it a problem if I end up giving the fluff arbitrary information?"
"I can nix this go as soon as I leave the bar, but will you know if it decides to send another girl here to beat us up, or pull out more less fluffy resources?"
"I'm getting realtime on it getting information from what I'm saying, so probably."
It is not sure what 'nix this go' means. It comes up with guesses. It sounds like the unknown puella magi thinks she has a way to counter some projected action of the network. That is interesting. It comes up with guesses. It will hold off on actions that will provoke whatever she thinks she can do, until later.
"So what's tier three potential like in terms of possible wishes?"
"They have a policy about not telling you what anybody else wished for or giving suggestions."
"Ah. Hmm..." She thinks for a minute. "Emily, I'm casting the Gate. Lemme put a Si Vales on you so I can signal you if you need to remove something and you can go in, alright?"
"I'm holding the fluff," she points out, but comes over so Edie can put a silvery dot on her forehead.
And Edie creates something that looks an awful lot like the Mind Mirror, but instead of a mirror it's an ornate marble doorway.
"If my sister or I wished to be able to make doors to this place whenever we wanted, would that be a valid wish?"