She rolls her eyes. "You said you wanted immortality and asked what I would want in exchange for granting it to you. I said your soul."

"Ah, that question. Since you interrupted my contemplations," he says, a little pointedly, "I have not had sufficient time to consider your offer."

He thinks for a moment, and realises a potential reason for her insistence on haste.

"Would you prefer that I release you for the present, and summon you again once I have reached a decision?"

"If it's going to be that long, I'd like to take the opportunity to look around this world for a while."

He considers it. 

There is a strong possibility that she might get up to various destructive or otherwise inconvenient activities, but she has claimed to be 'friendly' and interested in cooperation. Specifying a desire that she refrain from causing problems would only be taken as insulting, and increase the chance that she might be inclined to such behaviour out of spite. And given the course of their interaction so far, he would be best served by catering to her wishes as far as possible, unless there is a serious personal cost to be incurred. Letting her loose on the unsuspecting population does not qualify.

"Very well. I shall be finished with my contemplation when the clock next strikes twelve; it would be a great convenience to me if you would return at that time." 

In truth, he does not require so long as all that to decide, but since it is now the small hours of the morning, he would like the chance to sleep on his decision.

"Don't do anything silly while I'm out."

...

He probably deserves that. Call it revenge for addressing her as 'child'. He should count himself lucky that she has done no worse - yet. 

She grins at him and goes to find an exit.

Jeremiah remains sitting on the floor, taking a few moments to simply breathe and relax now that he no longer has to spend every second attempting to stay ahead of a faerie trickster. 

One he is calm, he finds another piece of chalk in his cabinet and continues drawing out his second circle. The salt seems to be no protection; he does not bother with it. He does, however, repeat the order of operations, closing the circle only after writing out everything else. After going back and reading the bindings he wrote for Evanathe, he believes he has found the loophole which allowed her to leave the circle, and makes an attempt at redrafting that section which takes him most of an hour.

About an hour after Evanathe left, he is confident in his circle, and is ready to finish it and summon a second faerie. 

There's not really much to see in this sleepy country town, and she can't go far and risk losing her place in the dark. Which means she's back in time to break the section of floor he's working on out, raise it up, spin it over and drop it back down.

"Tsk, tsk. Didn't I say not to do anything silly?"

"I consider it eminently sensible to seek independent verification of the most important details before committing to an irreversible bargain," he blusters.

He's rather shaken by the extent of her powers, but endeavours to conceal this. He also refrains, once again, from objecting to being patronised. She is, assuming her story is true, several hundred years older than he. 

It helps, a little, if he imagines her looking like his grandmother. 

"But if you call someone else, what guarantee do I have that you won't make the deal with them? I'm protecting my interests."

"Of course it is in your interest to prevent me from summoning. But that does not mean that it was not in my interest to make the attempt," he points out.

"Regardless, it is clear that you will not allow me to verify your claims by any external means. With that in mind, I instead have a few questions to ask you. Is that more agreeable?"

"Go ahead."

Where to start? He decides, arbitrarily, to proceed in chronological order.

"Firstly, by what means do you intend to extract my soul? Will it cause any pain, or other immediate side effects? How will I know that the transfer has been successfully carried out?"

"It's faerie magic. You won't feel a thing."

Really.

"Will there be any effects on the rest of my life?" he checks next.

"Say, my ability to enter churches, or make moral decisions?"

"You'll be more selfish, but you're already only looking to make yourself immortal, so I wouldn't worry about it."

So far, she has an immediate answer to every question, although the answers themselves are not particularly detailed. The very speed and confidence of the answers makes them suspicious, though: this cannot be a situation which occurs frequently, and she has admitted that she has not been summoned at all in a while; he would expect more hesitancy as she tries to remember the information.

On the other hand, there have already been indications that her memory is better than his, and he may be mistaken in judging her as he would a human. Perhaps she can truly recall the information so readily, and is simplifying her explanations so as not to overwhelm the puny mortal with too much detail.

"How much more selfish? How does this manifest; is it an increase in some kind of impulse towards selfishness, or a lessening of more altruistic instincts?"

Shrug. "Eh. Kinda depends on you."

So, she is avoiding providing further detail; he is beginning to be suspicious that she is reaching the limits of her creativity, not her knowledge. There is no shame, especially for a woman, in admitting ignorance about the precise details of some minor point. 

"In what way? Does it change based on my soul, my personality, the individual decisions I have to make - "

"Your soul is like, the bit that does the caring-about-other-people. Some people have big souls and losing them changes them a lot. Some people have small souls and don't really change."

"That should be no problem, then. It seems my soul is smaller than some."

That reminds him of another question.

"Can you determine by looking the size of a person's soul? Would you notice someone who did not have one?"

"Only if I tried to take it."

Well, isn't that convenient. 

He tries to remember the other questions he had prepared.

"Does immortality, of the sort which you propose to trade me, protect only against death from old age, or from dying in full generality?"

"Just old age."