Slavery?

"So you made me into your slave, my king?"

The girl froze, for a second before quickly stuttering out the response

"No, I saved you from certain death, I didn't make you my slave."

A small smile spread across my lips,

"So you will release me from my shackles then my king?"

The girl paused, a slightly awkward silence began to fill the room, after a while, she shifted her eyes away from me and spoke.

"I can't do that, removing my piece will kill you."

*She isn't wrong, removing the piece will kill you however not for the reasons she thinks it will. The piece is now yours, you are not under her control however the piece is fused to your being, making it nigh impossible to remove.*

'Wait so the piece won't allow her to control me?'

*That is what I just said, yes.*

'So the question now is, do I play the fool and wait for a moment to strike or level with her?'

*How about you play the way you always do?*

'I don't know what you are talking about.'

*Yes you do, the hidden village, being abandoned by your parents for being weak, begging and killing for food, the life of the forgotten and beaten, you play it so well.'

'Who shit in your cereal? How do you know about the Hidden Village?'

*To beings such as myself, very few things are actually hidden. Did you know God is dead? Oops, spoilers.*

'...'

*Come now, we have a play to act out, begin acting*

"I'm going to level with you Sona, I belong to a hidden faction that very much wants me dead, me being alive doesn't sit well with them and me being with a Devil will make everything 10x worse. It is in both of our interests that you let me act independently from you, that village of Youkai are extremely powerful and extremely vindictive."

*Why did you tell her the truth?*

'She is similar to me I can feel it, instead of being a selfish bastard, however, she wants freedom for more than herself. In fact, why can I feel that? What did you do to me?'

*Nothing, the Evil piece.*

'Ah'

Sona looks at me in disbelief, we continue to stare at one another for a few minutes that feel like an eternity.

*Tick Tock, Tick Tock*

Sona finally sighs,

"Why did you lie and say you hadn't even heard of angels when you knew about them?"

A small smile spread across my cold face,

"I was abandoned by my family at a very young age, I was harassed and bullied by every supernatural being I have ever met, stabbed, beaten, starved, all I want is to be free. I will kill to achieve this, I will steal to achieve this, I will do whatever it takes, so may I ask again, will you choose it to free me willingly?"

A sad look occupied her face, her eyes that were looking off to the side, looked back at my face.

"Prove to me that you are a Youkai"

In response, my small yellow ears erupted out of my head on their own, my tail forced its way through the scraps of leather I called shorts. This is not my usual look, I was born to two cat Youkai, there is no such thing as a mouse one...

...

...

'Oh fuck, I fused with that little shit from before, you did this didn't you?'

*Yes.*

Sona gaped at me, she reached out and gently touched my ear, soliciting a small moan from me.

She blushed, taking a step back,

"I'm really sorry about that, what species are you? I have never seen anything like that before."

'Why did I moan?'

*Because it felt good? Sometimes, I swear you-*

"It's ok, like I said, hidden village. Do you have somewhere I can sleep for the night, I don't want to sleep rough if I don't have to. For now, I'm willing to remain in this peerage as long as you do not force me to do anything and if you want me to do anything, I will need an incentive to do so."

Sona nodded her head, seeing that this was the end of the conversation, for now, she turned and shouted,

"Tsubaki, can you show"

Sona looked at me,

"Mason, my name is Mason."

"Can you show Mason to the male dorms, he will be enrolling her starting tomorrow, right Mason?"

*Take it, we need to be in a safe sleeping situation to enter the other world.*

'What do you mean?'

*You will see soon enough.*

A young bespectacled woman with long straight black hair entered the room, bowing to Sona, she looked straight at me.

She had a unique feature, her eyes were two different colours, one a ]violet coloured one, the second a deep brown. I found myself staring at her,

"Beautiful"

I muttered,

"For now, Sona, she will be my incentive."

I remarked as Tsubaki lead me out of the room...

The trip to the dorm room was a silent one, Tsubaki, had clearly heard what I had said to Sona, whenever I tried to strike up a conversation with her, all I got was a rushed and cutely spaced out response.

As we entered the dorm, a familiar yet eerie voice entered my head once more

*Tutorial quest: Evolve! :

1. Reach level 10

2. Amass 250 total stat points

3. Reach rescue team rank E

Rewards: Evolution, Partners section of the system, Item: Rescue Badge Deluxe, 100,000 poke dollars.*

End of Chapter.

So the Mc's backstory will all be OC, none of it will be canon obviously however it will play heavily into the story going forwards.

As to his way of thinking, as I said in a comment a little while back, I'm going for a chaotic natural character, which is defined as:

A chaotic neutral character is an individualist who follows their own heart and generally shirks rules and traditions. Although chaotic neutral characters promote the ideals of freedom, it is their own freedom that comes first; good and evil come second to their need to be free

This will become more apparent as the Mc gains enough strength to start to have an influence on the things that go on around him, the next chapter will be in the Pokemon world.