The Fist Saint had realized the moment Theo appeared, he already knew he would be safe.
There was no way the Fist Saint would attack Theo because he needed to make the connection between him and the King Class Monster. Just making him think that way was enough to buy a few minutes.
In other words, he had been preparing to call the reinforcement when he came out.
Although he didn't know how he could do it, the Fist Saint knew their plan would become extremely dangerous the moment this was exposed to the monsters.
Now that the Dark King had appeared, Theo could finally get some air, wondering what he should do next. Even with the Dark King, he didn't believe they could defeat the Fist Saint.
So, he needed either the quality or the quantity. If he went for the latter, he would need to meet a few other King Class Monsters. If it was the former, he would need someone strong enough to fight against an Authority Level Figure.