"Okay, explain from the top. Because I honestly don't understand what could have possibly led you to that conclusion."
"No no no dad, this is the part where you reject her outright not listen to her reasoning."
Arthur tried to get Hades on his side but-
""Be quiet for a second Arthur.""
-it was already too late.
"So it goes like this...."
Cattleya told Hades about the warning she gave Arthur after he fought Owen and about how Arthur fought the Valkyrie, who was an actual legendary realm, though she has no idea how Arthur was able to bring her down to the grandmaster stage and finish her off.
When she was done telling Hades everything, he simply nodded in understanding and spoke up.
"It's Ai-."
"Dad!!"
And he was interrupted by Arthur.