After leaving the Insect Domain, Klaus had a lot of thinking to do.
First, Asha was indeed a monster in her own right. Though he discovered that aside from contracting and talking with insects, she couldn't do much else, he was still impressed.
This also meant that the moment she fully awakened the forge, she would gain some incredibly overpowered abilities, allowing her to modify her insects.
The second revelation was the discovery that she possessed a forbidden abomination. That realization placed Klaus in a perspective he had never considered before.
If Kai—as she called him—really just woke up in a cocoon, then what else has awakened, and how many of them would be this benevolent?
Kai had willingly become a companion to Asha, which meant he was bound to her and could never betray her.
Of course, he was a forbidden entity, so who knew what else he could do? But that was beside the point—he had accepted his servant role.