Because the subordinate soul had resisted before, the Blood Demon had prepared some measures to forcibly suppress the subordinate soul during fusion, in order to complete the fusion and acquire the subordinate soul's strength and gains.
However, to his surprise, the process of fusing with the subordinate soul went extremely smoothly, without any resistance. The only thing that puzzled him was why the subordinate soul seemed to be taking root within the Divine Soul.
It gave him the impression that, although the subordinate soul had merged, it had not dissipated. Instead, it coexisted with the main soul in some way.
In the back of his mind, the Blood Demon felt something was wrong, but he couldn't pinpoint the source of this uneasiness.
As the fusion with the subordinate soul proceeded, the mysterious Runes that were hidden within the Divine Soul also began to emerge. Yet the Great Technique that the subordinate soul practiced had not manifested.