2: You can't make an equivalent trade if you cheat.

"Wow, I'm screwed," Jackeline said as she realized where she was standing, in front of her was a blond man holding a bottle with a black creature in it.

It seemed she had surprised them when they entered the room and found it, everyone was silent until Jackeline decided to speak.

"I would like to learn alchemy from you, sir, in the meantime I can offer you my loyalty," she expertly knelt before the blonde, but her words and actions were entirely directed at the being in the bottle.

"Strange, you are strange, how did you get into this place? No, why do you know that I can teach alchemy and why do you give me your loyalty?" while the blonde didn't know what to answer, the being in the bottle took over the conversation.

"You could say that fate led me here, I don't know how I got in, I don't know why I know about your ability to teach alchemy, but I want to follow you for a reason. I want to remake my body with alchemy and in return I will be your most loyal sword, I want to learn alchemy from you, and in return, I will give you my knowledge of potions and summoning spirits," Jackeline said with conviction.

Many will think it's stupid what she's doing, how can she pledge loyalty and exchange knowledge with a being who is one of the pillars of the future of this world?

Murtagh described Jackeline very well, but she can bend and stretch for her purposes, and she had experience dealing with manipulative people like Galbatorix, didn't she know how to deal with the being in the jar? She did, and very well.

That kind of person would never trust you, she was like that herself, but if you were useful to them, if you kept up the facade of obedience, they wouldn't mind giving you benefits. She also never minded giving her loyalty to those who were stronger or wiser than her, because she could always learn something.

 They are proud of their knowledge and power, how could someone like Jackeline surpass them? For this type of person, Jackeline was someone they could invest in and use as long as it brought them benefits.

But she also gained a lot from them, she knew that her weakness was ignorance and lack of power, and that's why she put aside her pride to learn and improve herself. She did not lie, when she saw the world she was in, she quickly made a plan to overcome the situation and gain benefits from this world.

"Well, follow me and learn alchemy with me. With pride in her voice, the being in the vial ordered Jackeline, who quickly got up and stood behind the blond man.

"Hello, I...

"I don't care who you are," Jackeline interrupted the blond man coldly and glared at him. Her bright blue eyes simply saw him as a piece of meat to be thrown aside, no life, no dignity, no rights, just deep contempt.

This shook the blond, he felt it was not a good idea to dialog with this strange old woman, so he simply walked to his desk and left the vial on it.

So they both learned alchemy, from the simplest to the most complex, as if the knowledge of the being in the jar was infinite, she could easily give them new teachings, tips, and points to note.

Alchemy is the science of understanding, decomposing, and reconstructing matter through the use of energy, either one's own or that of the environment. Governed by the law of equivalent exchange, what you offer is what you get, if you give a bar of gold, you will receive something of equal value.

It was so simple and complicated at the same time, she knew why human transmutation was taboo, simply because a soul was of such a high value that it was impossible to pay for it with just the ingredients that made up the body, no wonder the alchemists always failed, they didn't give anything in return and suffered for breaking the rules.

But not only matter, if you understood energy, you could break it down and reorganize it, that's why it was possible to do alchemy related to fire, by understanding heat and the process of how combustion was created, you could create fire alchemy.

Since Jackeline had a deep knowledge of magical energy, she could replicate her spells with alchemical circles and formations, but it was boring to have to constantly calculate and draw everything, if she didn't open the door of truth, she couldn't do much.

In this world, of course, there was no 'magic', but she was the source of it, so her spells worked, even her language as if the whole concept of the ancient language had clung to her being and followed her to this new world. 

Fulfilling her bargain, she taught him how to make potions and how to summon spirits to the being in the jar; the potions she solved with knowledge of the local herbs of this world and alchemy, but the summoning of spirits was interesting.

She didn't think this technique would be useful in another world outside of Alagaësia, but when she summoned a small colorful ball that floated freely in the room, she realized. The spirit world is a concept that exists in many fictional stories, and it seemed to be something more than just an attribute of a single world, but something more that encompassed other worlds, perhaps all worlds out there.

This made her even more certain that this knowledge was dangerous, but this world didn't matter to her beyond alchemy, and what the being in the jar would do with her knowledge didn't matter to her as long as he kept his end of the bargain.

...

Xerxes was destroyed, Van Hohenheim became immortal, and in denial of the cruel act that destroyed an entire civilization, he made a pilgrimage to the land of Xing, Father obtained a body similar to that of his male apprentice and intercepted a certain number of souls, creating a blood-red stone.

"Let's see, how are you going to use the fifth essence, the Philosopher's Stone?" asked Father to a decrepit Jackeline who, even in her weakness, still had a great anger in her eyes.

"I want you to see what I am about to do..." She received the Philosopher's Stone and admired it for a moment before shaking her head.

She was beautiful, she was powerful, but she had a soul. She could kill without blinking an eye, but she would never mess with souls, even if she knew the darkest magic of Alagaësia, it was taboo for her and a way to limit herself. 

But not messing with them didn't mean she couldn't benefit from them. She created a complex transmutation matrix, in the middle of which was the name of the ancient language, which no one could understand without her permission. This caught Father's attention, but he quickly turned his attention to what she was placing in the matrix.

Not only did she place the Philosopher's Stone, but she also placed a vial of red blood that seemed to glow, as well as a strange blue crystal that seemed to emit its glow. She stood in the middle of the circle and activated it, causing it to emit an ominous dark purple color. 

"Understand!" 

"Decompose!"

"Rebuild!"

"Rebuild my new body!"