"The geases have to be done out loud because of how I designed the power - I like to make it inconvenient for myself to do things I oughtn't - but I can install ground rules now if you don't have questions about how they're going to work or anything," Bella says to Sandy.
"New coins you make will appear somewhere in contact with your person. Especially since you're highly likely to produce coins in your sleep and not be able to direct that accurately, I want that automatically directed to someplace safe - even someone who travels to Amalthea and sneaks into your bedroom shouldn't be able to take your coins. And I really don't want you to give them away, either. You can make small, discreet wishes for friends, but the idea of all the secrecy is that I don't really want to have to explain where my magic is coming from anytime soon, and someone clever could get a lot of mileage from knowing who else has it. That one we can do with a geas or with a limitation on your coin repository preventing the coins from leaving it except by a wish from me or direct use by you."
Since he doesn't exhibit a preference between the geas or ground rules option, and since she trusts ground rules to hold up against more situations than geases, she shrugs and implements it as such. And she makes him a chain like hers. She hands him his new expansible coin-chain. "Here. I have one like it, but you can't see it. Wear it. It won't come off unless I allow it, so you aren't going to pull it off in your sleep or whatever. It and coins on it will go through anything that isn't you or me, it and coins on it are invisible to anyone who isn't you or me, coins will go on it when you make them, it'll get longer if there get to be a lot of them, you can make wishes with coins on it but only I can take them off."
"It's entirely possible that you'll be able to make all the coins you need to overnight. If that turns out to be not the case, I recommend wishing yourself some sort of regeneration power if you want to handle them yourself, or I can agony-beam it for you," Bella says in as businesslike a fashion as possible.
She takes a deep breath.
Hex goes.
"Wonder what color your coins are," she says idly. "Everybody's are different."
"Experience some amount of pain - I'm in the habit of biting my cheek - and move it, left to right," says Bella. "Isn't that weird? But it makes sense now, doesn't it."
His chain acquires a triangle; he holds it up to inspect it. It's not glossy like Alice's or glowy like Bella's or sparkly like Elias Frobisher's: it's a dark, mottled red-purple like the inside of a bruise, and it's flat, without texture or shine.
"My favourite colour," he says happily. "Cool."
"Brainphone me if you have questions or whatever. Otherwise I'll expect a batch of coins in one Martian week."
"Sure," he says. "I'm probably gonna bug you about a teleportation power when I've got a spare hex to cover it."
"You can wish for a copy of a power I have without actually having me explain what you're copying," she says. "You might not want to do that with all my powers. For instance, my regeneration comes with anaesthetic. But I like my teleportation design enough to recommend it to you, and it's simpler to operate than some of my arsenal."
[Nope! I believe you said you wanted to live here if I hired you, which I have decided to do.]