From the moment Konrad appeared, the Evil and Neutral Bodies knew they weren't his match. They put on that desperate struggle, all so that they could cheat the main body into thinking they tried their hardest. Meanwhile, they planned their rebellion. With the Evil Body outwardly powerless, when the time came for Regretless to surrender to Celestial Slaughter, the Neutral Body would keep his attention, thereby making him forget about the fallen Evil one.
At the critical instant, the two would strike, overwhelm Regretless, destroy his soul, and seize the body! Afterward, becoming a True Almighty was only natural. They could then dispose of all their enemies. Never did they expect that Celestial Slaughter would provide them with such a golden opportunity, and without hesitation, they jumped on it!