"Kill me?" Arion asked as if he is surprised. "Layla, your brother, Alfonso, can't even put a scratch on me. What are the chances of you killing me?" From way back, Arion has observed Layla and Alfonso, and since then, he noticed that Alfonso is always holding himself back from his sister.
He can tell that Alfonso is way stronger than Layla, and he also sure that Layla knows that fact.
"That may be true, but there is someone who can put a scratch on you. And I think you know that person." Layla said referring to Arion's wife. Though there are others who can put a scratch on Arion, Mary is still the one who can do that so easily. It's because Arion will let her, it's because Mary has quick reflexes.
Before they even got together Mary and Arion got into a fight. And that is how Layla knows about this fact. They were enemies to the first time they met.