The slave contract, unlike the slave seal, was much rarer and more useful.
When a slave seal was placed on someone, it rewrote their will and transformed them into the person the master of the seal desired.
Although this had its advantages, the disadvantages were significant as well. First, the slaves' personalities would completely change, making it impossible to turn them into reliable spies.
Moreover, the slave would also lose much of their combat effectiveness, as nobody understands their strength better than themselves, and the personality change has a deep impact on that.
However, with the slave contract, this problem was completely mitigated.
As the slave contract ensures that as long as its conditions are not violated, the slave would retain their own free will and would not turn into a different person.
The slave contract was also used during alliance formation, as it could also set conditions for the master, thus allowing the slave some freedom.
So Bai Chen was quite shocked to learn that Zhang Yu had a slave contract in his possession, "I didn't think you would have a slave contract in your possession," he commented.
"You know about the slave contract?" Zhang Yu showed a slight surprise as the slave contract was something only a few people knew about. "Well, that makes things a lot simpler."
"Since you already know about the slave contract, are you willing to sign it?" Zhang Yu asked. "I will be completely loyal to you as long as you help me destroy the Book of Satan. Of course, I will wait till you are strong enough."
Hearing Zhang Yu's offer, Bai Chen fell into contemplation for a few moments. The idea of having a trained assassin as a loyal subordinate was certainly tempting to him.
Moreover, what Zhang Yu said also made sense; if he had an insider helping him, he would have a much easier time avoiding the retaliation from the Book of Satan.
After thinking about it for a few moments, Bai Chen turned to Zhang Yu and said, "Fine, but I have a few conditions of mine as well."
"First, you will help me train people to become assassins and informants."
"Second, I will be making an organization specializing in information gathering and assassinations called Anquan Zhongxin, you will act as its head in my stead."
"And finally, if I ever feel like my life is in danger because of your request, I will hold the power to finish both your life and the contract."
While stating all this, Bai Chen's eyes never left Zhang Yu's face, and finally, he asked, "Do you agree to all this, or should I kill you now?"
Listening to Bai Chen's demands, Zhang Yu didn't find them strange, though he felt weird about the name Bai Chen chose.
Still, he nodded and took out a slave contract from his spatial ring, "Alright, I'll let you write down the conditions, and then we can sign it."
Bai Chen took the contract from Zhang Yu's hand and quickly wrote down their agreed-upon conditions on it.
Then he bit his finger and dripped a drop of blood at the bottom of it. The blood quickly seeped into the yellowish paper, giving it a slightly red hue.
He then handed the contract to Zhang Yu, who first reviewed the terms written on it, and after making sure they were correct, he also dripped a drop of blood in it.
As soon as Zhang Yu's blood touched the contract paper, it started to glow in a bright silver light, bathing the surrounding area in its glow.
The next moment, the light divided into two spheres of light, and they quickly merged with Bai Chen and Zhang Yu.
When Bai Chen saw the light ball merge with his body, he sensed that there was some kind of shackle that was placed on his soul, and if he tried to forcefully break it, it might kill him and remove him from the cycle of reincarnation.
Bai Chen had already expected it, so he wasn't surprised.
Meanwhile, Zhang Yu was also feeling the same thing, but it was way more intense than what Bai Chen felt, as he was the slave, so the binding on his soul was also a lot stronger.
Zhang Yu ignored the discomfort he was feeling and instead took out a few pills from his spatial ring and ingested them.
The pills turned into liquid the moment they touched his mouth, and a sense of comfort started to spread in his body.
Mist started to rise from his wounds, and even the flesh on his right shoulder started writhing.
Bai Chen watched in amazement from the side as the pills quickly started to show their effect. In just half an hour, Zhang Yu was completely healed, barring his still half-regenerated right arm.
"To think you even have a Nirvana Pill."
Nirvana Pill, unlike a normal healing pill, was a thousand times more precious.
Refining it not only required the fruit of rebirth, something that can only grow at a beast corpse with a highly concentrated phoenix bloodline, but also a Great Grandmaster alchemist to personally refine it.
And these were just the main requirements, there were also a lot of other precious herbs used in the refining process, whose combined value was enough to bankrupt a second-grade power like the Azure Dragon Sect.
Due to its incredible healing properties that can pull anyone from the brink of death, there was always a demand for the Nirvana Pill, but never a supply, making it one of the most valuable pills out there.
And seeing Zhang Yu casually eat one made Bai Chen's heart ache.
'Damn, if this pill were placed in an aution, it would have generated enough income for me to not worry about my finances for a long time,' Bai Chen thought to himself, though his face remained expressionless on the outside.
"I got lucky and found it in an inheritance site when I was on one of my missions," looking at the astonished face of Bai Chen, Zhang Yu told him the source of the pill.