It began with my "little sister" spell,

And ancient vampire-inherited relics.

Only the little sister's spell succeeded in its purpose.

Because of that,

We were "doppels" possessing a will in being born.

And those copies... started some kind of rebellion?

Fed up with... old, moldy pacts?

Incidentally... the one now kindly making an opening in your stomach is the original.

With a long life of confinement, our power dynamic with the original has been reversed,

To the point where we can manipulate her behavior like this.