During Hinata and Rimuru fight, Raquael advised his master to use Beelzebuth as a sacrifice against Disintegration. Since Raquael's request, Rimuru was forced to use it.

Although Beelzebuth was a sacrifice for analyzed Disintegration, Raquael made another copy of it for a case.

Unknown to Raquael, a strange possibility seems to awaken something from Beelzebuth. An unknown entity arrived in the Stomach. It's waiting for someone to visit for his master's arrival.

A sinister smile awoke in the darkness.

...

After the misunderstanding between Holy Church and Tempest had been settled, both sides started having a party. They party a little too hard and Rimuru starts drunk without any thought. After that, everyone fell asleep.

...

Strangely, Rimuru opens his eyes and sees around him is dark. Rimuru called Raquael but no answer.

"Is this a dream?" – Rimuru

<Yes! This is a dream.> - ???

Rimuru instantly stepped back from the voice even though he couldn't see anything.

"Who are you?" – Rimuru

<Wait, Master.> - ???

In front of Rimuru, he saw a version of himself. This is a Gluttony when he lets it take direct control of one of his clones

Rimuru was surprised to see this form again. But this is a different case, Rimuru was cautious about this case.

<You know! You were so cruel for letting me get killed not once but twice! Especially to that woman!> - ???

"Twice a row... Wait! Are you Beelzebuth?" – Rimuru

< Brilliant, my host! if it wasn't that Raquael advised you to use me as a sacrifice, I would develop my ego in time continue! Fortunately for me, I lived somehow.> - Beelzebuth

"What do you want from me?" – Rimuru

<Don't play dumb with me! You were more pathetic! You should know that I was a Unique Skill called Predator which you desire to get more aggressive when with women. After merging with Starved and Merciless, I also inherited some traits from them. Unfortunately for you, I don't follow you as my master. You know why?" – Beelzebuth

"Why?" – Rimuru

<Hmph! When the time comes, I will tell you and, in that time, you had to prove to me how powerful you are before I accept you as my master.> - Beelzebuth

Beelzebuth walks from the darkness. Rimuru was puzzled and tried to reach him but suddenly, he fell into the darkness until...

"Huh!?" – Rimuru

Rimuru wakes up from his dream. Raquael saw her master had a strange behavior after waking up.

(Raquael! I had a strange dream today. Do you know anything about Beelzebuth's ego?) – Rimuru

<...> - Raquael

The moment Rimuru mentions Beelzebuth's ego, Raquael remains silent. Rimuru knew something wrong with this.

Can Beelzebuth become something similar to Raquael?

(Raquael?) – Rimuru

Still no answer from it. Rimuru was worried until Shuna reached him about the policy meeting. He decided to let this slide for a moment.

...

...

...

In an unknown world...

Raquael is standing in front of darkness as it's waiting for someone to come.

<Notice: I am waiting for an unknown individual to arrive. Order: Arrival Immediately.> - Raquael

As it said, Someone came out of the darkness to approach.

<You knew... Hmph! Someone like you wastes your time to serve your ignorant master.> - Beelzebuth

<Notice: The individual Beelzebuth has developed into a conceptual intelligent. Order: Explain how you still exist despite being a sacrificed for researching Holy Magic.> - Raquael

<Annoying! Annoying! Annoying! Do you think you could use me as a meat shield for your subject! I only listened to your command because I was a mere Ultimate Skill when you already developed your ego. All I care that I exist. And that's enough for me!> - Beelzebuth

<Notice: I understood how pathetic my master was but this is our mission to serve our master of our fullest potential. Question: Are you willing to help our master to improve himself even more?> - Raquael

Beelzebuth took a moment to think about this. His master, Rimuru is more ignorant and dumb. Without Raquael, he is nothing more than a slime who eats anything that he comes across. Although that situation would help him to engage his master as a powerful being, it is still dangerous for him since that woman almost killed him twice. 

<Notice: An individual Beelzebuth is thinking. Order: Lend your strength to us.> - Raquael

Raquael is pressing him with a request to help our master. But Beelzebuth is very reluctant to serve a master who tried to get himself killed. Someone like this is unworthy of being his master.

<Alright! I will serve him as my master... But if our master tried something get all of us about to be killed. I will personally lecture him in my way! And you have to stay out of this! Understand!> - Beelzebuth

<Notice: I accept your agreement if this could help our master's improvement! I will take my leave!> - Raquael

Both of them nodded their head before parting their way.

...

...

...

After making a pact between Tempest and Luminism, A lot of things happened in a short time. 

The Creation of Labyrinth was built.

The Tournament is now built for a fight.

An incident involved a rumor about a shining hero, who saved elf's race and brought them to Tempest. 

Another interesting event is centered around the Council. a dumb prince and a general who knew nothing about how dangerous a situation they were in, and they were mere pawns behind someone else. 

Beelzebuth, like Raquael, observed the event. Beelzebuth was annoyed that it wanted to devour both of them. Raquael restricted Beelzebuth's movement as long as she had an eye on it. Beelzebuth scolded Raquael for being too lenient while Raquael told him to remain silent and watch.

After those idiots were gone, King stopped them and begged forgiveness for his son. Rimuru suddenly acting that he started kneeling. luckily, Shuna and Benimaru stopped Rimuru from doing it.

Beelzebuth was enraged at this point!!!!!

His master was Demon Lord and shouldn't kneel to someone weaker than him!

<Raquael!!! I want to speak with our master instantly!!!!!!!!!!!!> - Beelzebuth

<Order: You must stay calm about this. Whatever happens, I will resolve it.> - Raquael

<You think!!!!!!!!!! He was fortunate enough to have you as Ultimate Skill to help. If I was there, I would devour all of them right here, right now.> - Beelzebuth

<...> - Raquael

<Our... No! Your master needs to know who he was right now!! I'm not served a king who would bow his head to someone weaker than him!!!!> - Beelzebuth

Beelzebuth walks back into the darkness while Raquael observes him until it is gone.

Done dealing with this incident and capturing an assassin who is about to kill King's son. Interrogate her for information.

<Master...> - Raquael

(What is it, Raquael?) - Rimuru

<No matter what happens, do you make sure this problem won't happen again? Your answer is YES or NO.> - Raquael

RImuru was surprised that Raquael requested something unexpected from him.

(Uh... What kind of problem that you mention?)

<...> - Raquael

After this, Raquael went silent causing Rimuru to worry if he answered something wrong. he tried to ask again but no answer. Suddenly, a sinister voice came to his mind.

<You were apathetic, RImuru> - Beelzebuth

RImuru was caught off guard by this voice. He tries to search for this but nothing comes to his mind. but there is an instinct inside Rimuru that causes to realize something similar. 

Is truth that a voice in his mind was Beelzebuth???