Pleasant Daydreaming.

The more souls he brainwashes and grafts, the more memories he has at his disposal to brainwash. That's why someone like the great mother was sure that no one would be able to steal the memories of her soul fragments without getting a memory backlash and being brainwashed. Unfortunately for her, he had Origin essence to maintain the integrity of his consciousness. 

Malekite was bombarded with memories from different entities so she stopped struggling. Legion-7 stopped at that point and went ahead to graft her soul. Any more memory infusement would have made her mad. 

His reward for his hard work came swiftly. Her soul melted into his soul force and empowered it. It is the first time that soul grafting has empowered his soul force directly. Soul fragments usually enhance his soul, not his soul force. 

"This is not bad." He muttered. "I didn't need to create and fuse with a concept to increase the power of my soul force."