He is of the opinion that the demon god put the heart of Carnage into his body because it sensed his powerful soul. His powerful soul probably intrigued the demon god who then decided to create a bigger connection between them so that a stronger channel would be formed between them.
He expected the demon to try and kill him immediately for his soul instead of talking to him. So he asked why the demon god was not being forceful with him. After all, he is already trapped.
The voice in his head sighed. "I like your determination. I don't want to perform a forceful takeover so that I will not rob you of your will and originality. Originality is needed for Creativity and Creativity is needed for Art. In other words, I want to preserve what makes you special so that you will create more works of Art. It is so that CARNAGE will become stronger."