It's a little surprising; normally she is permitted to enter random forests of her own will. But not that much.
She starts walking, looking for whatever inane plot she will be required to participate in/thwart this time.
Eventually she sees a cottage. She makes for that--random houses in the woods are prime weird shit locales.
She knocks on the door. "Excuse me! I don't know what's going on here but I'd rather get it over with sooner rather than later so I can go home!"
The door opens slightly. She opens her mouth as though to say something, pauses, then says instead, "Master isn't home right now. May I invite you in until he returns?"
The minion opens the door farther. She's wearing a dress made of leaves and has wings that are also made of leaves, albeit much larger ones.
As soon as the door is closed, the fairy says, "And you're a mortal and you need to go home as soon as possible, ideally before he's back. I wouldn't have invited you in but I'm under orders but I'm allowed to speak freely in the house with only a couple more specific restrictions. I don't have to chase you if you turn around and go back the way you came; can you? Was it a stable gate?"
"I just appeared here. I'd love to go home, but this kind of thing happens to me a lot; a weird thing happens to me and I have to deal with it. I can defeat it, even if it would narratively inappropriate, but running from it never works. So your master is evil, I'm guessing? And you're not his voluntary minion. So I have to defeat him and free you, I'm guessing."
"I don't entirely know what you're talking about, but if you came through a gate it ought to work both ways. If it was a tear you have a bigger problem. And if you're here when my master gets back he'll do his best to get you too."
"Don't tell him your real name and don't eat anything you didn't bring with you."
"I'm not allowed to tell you my name but I can eat your food. If you give me some you can rescind my orders and we can both be out of here before Yellow even gets back."
"I don't know what either of those things are and it doesn't matter as long as they're food and from the mortal world and come out of your hand."
Promise takes it and swallows it whole. She shivers. "Say, 'I rescind all your orders'."
"Thank you," says Promise, suddenly relaxing all over. "I'm going to pack a few things, burn this place to the ground, find someplace relatively sheltered to make you a gate, and fly away. Just a minute." She ducks into a side room of the house and comes out soon after with a bag.
"He wasn't as bad as my last master. I had leftover orders when Yellow bought me or I would have been long gone." Promise leads Little Bird out of the house. She looks over her shoulder and the entire structure turns into smoldering slag, collapsing on itself slowly.
"Do not try to find my old master. I can get you a gate home. You'll be safe back in the mortal world."