Before, Ximao truly thought the twins were in the Space-Bending Realm Initial Stage, just like Wisfreya. They had been following her cultivation realm on purpose so they could stay with her while they took her soul pieces and blood.
Now, however, Caladara showed that the twins were actually in the Space-Time Middle Stage. On top of that, they displayed the strength of a Divinity Realm Peak Stage when they attacked her, and a pretty damn strong one at that. Simply put, any of them could beat Ximao.
He wanted the secret behind such strength. Anything that just cultivation alone wouldn't be able to provide. If someone had it, that must be these four. Ximao firmly believed that the 'expert backing them up' left many things that could help him on that front. "Strength. Truth be told, compared to other Divinity Realm Middle Stage experts, I'm quite strong. I can even put up a short-term fight against some of the more average Divinity Realm Peak Stage experts."
