Master Leon's soul had changed and became Merlin who was forced into this new Latitude Cosmos. He originally had intended to stay as he did in Stedman's body in the Void Zone, without affecting the self-awareness of the living being.
However, he had underestimated the natural order of this new Latitude Cosmos. Merlin's Illusory World had collapsed, and once he had entered this world, he had already been targeted by the natural order of this world.
Fortunately, Merlin's reaction was quick. He saw Leon, and quickly entered his body. However, he did not expect that the natural order of this world would be so tyrannical as to chase after him inside Leon's body.
The muffled sound earlier was the chase and attack of the new Latitude Cosmos chasing upon Merlin. Therefore, Merlin had to forcibly erase Leon's consciousness, and occupy his body. However, after occupying Leon's body, he had gradually forged a close connection with this new Latitude Cosmos.