Samuel's soul being controlled by Andrew did not prevent him from breaking through to the Demon King level, because he was breaking through to the Demon King level, not becoming a Demon King.
Samuel's system was the Ability System, not the Demon King System. The Ability System did not have so many requirements.
After signing the contract, Samuel impatiently asked, "Mirror Demon King, how are you going to help me break through to the Demon King level? Are we going to Hell War too? That probably won't work, because..."
"Because there are no other Ability Users in Hell, right?"
Mirror Demon King smiled. "Your second ability is to resonate with nearby Ability Users. The more Ability Users there are around you, the stronger you become."
"How do you know?"
Samuel was stunned. Only he and his brother knew about this. His brother believed his ability was too dangerous and had always suppressed him, even refusing to tell him what his second ability was.
Later, Samuel learned about it by chance. Enraged, he directly killed his brother and inherited Playground.
"If I didn't know, why would I seek your cooperation?"
Mirror Demon King said. This information had been deduced through analysis of various materials. He had no doubts about it, because he was just that smart—though in truth, it was Andrew's subconscious suggestion.
"That makes sense."
Samuel said, "That's right. My second ability is Ability Resonance. The more Ability Users around me, the stronger I become. Last time, when we teamed up to besiege Demon Prince, I could even tear apart New York.
"Among all Earth's superheroes, only Director of S.W.O.R.D. is truly stronger than me. No one else is my match, of course, provided the conditions are met."
Mirror Demon King said, "What we need to do is keep you