Since the Heroes were summoned, they were subject to intensive training which most was compliant with, and some were deviant.
They had no intention to fight for a Kingdom and risk their life.
They had said to leave the castle themselves and escaped the responsibility of being a Hero, or it was only the lies said to have the Heroes be unrespectful of the King himself.
It was under the wraps that they were assassinated in the capital. They left nothing but a droplet of blood in an abandoned alleyway.
Gladysius and his friends could grow much faster than the others.
They were well informed and knowledgeable, and even magic was such a basic concept for them that they were able to use it in such a short time's notice.
They were geniuses, prodigies. The King would only come to like them all, however, he had liked Gladysius the most.
He was like a dog that was obedient in his words despite his hobby to speak even when not spoken to.
He was the perfect puppet.