The more time Aqua spends on land, the more he'll likely start to learn the intricacies of human relationships. He'll probably get to know that there is a huge variety of relationship types between 'stranger' and 'friend' and 'lover'. Boiling it down to a mere three categories works for Aqua's purposes though. It tells him quickly where he stands with someone. Sub categories can come later.

"Dangerous?" That word doesn't match up with the Su-jin he knows. It doesn't sit right and feels strange. This kind man who's been so patient and helpful to him. This lovely creature who makes him smile so much is not someone he can imagine as being dangerous. "You were told to be together because you're dangerous?"

Aqua once more looks toward the house, toward the host who's somewhere inside. Su-jin's partner. The one who's made Su-jin into a better version of himself, he says. "Your partner sounds like a good person." Good to Su-jin. Good for Su-jin? "A good person who lead you here." To where Su-jin and Aqua could meet. To where they can stand here together, looking out over the water.