She knows Yellow, and probably Promise, and likely many or all of the people here, can give orders based on knowing someone's name. She knows the orders depend on the wording, though she hasn't nailed down how that interacts with this species fascinating lack of a language (the error messages from the TARDIS' translation field are rather hysterical). Lying might be failing to try to get along, so she'll just ask questions and see if she gets consistent and true answers. "Is it only names that activate the orders? Can you do it too? What happens with contradictory orders?"

"It's not just names, all fairies can do it, and recent orders take precedence."

None of those have contradicted anything Ms Frizzle has noticed, and also Promise can definitely give her orders and hasn't. "What else works then, other than names? And what constraints are you presently acting under?"

"The other way is food vassalization. And it's - too many to list completely, but a considerable number."

"Oh dear. And if, hypothetically, someone in your situation were to come across someone who was interested in changing that situation?"

"Well, they'd be forbidden from trying anything clever, unfortunately."

The Teacher will just have to be clever enough for both of them, then, but she'll see if she can't get a bit more data first. "Can you explain food vassalization?"

"If a fairy feeds a mortal or a mortal feeds a fairy, food that they have claim to - generally any kind of fairy food from a fairy or any kind of mortal food from a mortal will work but there are some potentially fuzzy boundaries - then the one who eats it is vassalized. This doesn't work if there's a preexisting vassalization between the two going either way. - we're forbidden to try anything clever, but if I just mention something clever I'm not trying it, and if you just copy my idea it's not that clever of you."

"You're quite right," she says, reaching a hand into one of the many subtle pockets on her fern-patterned dress. One doesn't spend countless years teaching small children without developing a habit of keeping an Emergency Snack on hand at all times. 

She doesn't want to risk being polite about this, when she doesn't know what contingencies Promise is under and she might only get one shot. Out comes a granola bar, clumsily unwrapped with one hand, and the end is in Promise's mouth in the time it would take a human to blink.

Promise swallows. "You might want the phrasing 'I rescind all your orders'."

"I rescind all your orders. And I apologize for the surprise; I wasn't sure you weren't ordered to try to stop me."

"Yellow's incompetent. I'd have been out from under him a long time ago if I didn't have some standing orders from my prior master. I can't feed you in return but your name will still work."

"I have all sorts of ideas for how to cause you to be informed of my name without technically telling you or letting anyone else overhear. Unfortunately they're all clever." She can't manage to explain any more helpfully than that, though she's still under orders to obey Promise, so that should be fixable pretty easily.

Promise gets her some paper. "Write it down," she suggests.

Oh good, using someone else's paper, nice and boring, not clever at all. She writes "Valerie", shows it to Promise, then pockets it.

"Never give me an order that I do not expressly request of my own uncommanded will, or that you do not sincerely without mental contortion believe to be in my best interest as you genuinely understand it. Except the reciprocal of this one if you so desire. I rescind all Yellow's orders."

"Never give me an order that I do not expressly request of my own uncommanded will, or that you do not sincerely without mental contortion believe to be in my best interest as you genuinely understand it. Commendable phrasing, I'm glad you're prosocial and Yellow isn't rather than the other way around. I suppose you'll be leaving the area now? I will." Not necessarily the dimension, mind you, now that she has a workable nickname she might stay and look around a bit more, but certainly the house and its vicinity.

"Yep, I'm going to pack some food and burn down his house and get out of here."

"Would you like a ride someplace? My ship can go anywhere you've heard of and a great many places you haven't. Including places with no other fairies or similar magic, which something tells me you might find a selling point."

"I'd object to being without my magic. But I wouldn't object to getting several continents away, if we can make a stop first." She's stepped into her room and is shoving fruit into a bag.

"I suspect your magic is thoroughly attached to you, most people's is, but we can always go somewhere else and then come back to this dimension if the other one doesn't suit. Where's your planned stop?"

"Sorcery doesn't work in the mortal world; I'd still be a fairy but I prefer to be a sorcerer." She has her bag packed; she lets herself out of the house. "It's north of here, I'm not sure how you mean to travel exactly."

She chuckles at "the mortal world". "I'm planning to walk to my ship, from which it's about a minute's travel to just about anywhere in time and space. Including your stop, and several dimensions that will probably permit your sorcery--which I'd love to learn more about, by the way."

"Several dimensions."

"Oh, yes, there are quite a lot of them. More than I've ever had time to count, though I suppose the Bus might know. She's this way, by the way," Corundum adds with a gesture.