so what's his type?

That man doesn't have a type. He has an OBSESSION with only ONE person

Ik where this is going! but mind giving more spoiler, what kind of obsessed top is he exactly

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In the novel, he literally puts in his will that if he dies, he wants ja-kyung to die also and be buried with him

And ja-kyung tries to run away from him several times but Il-hyun finds him every time and brings him back. He's absolutely crazy, but he really loves ja-kyung by the end of the story and ja-kyung loves him back. They really match each other's freak.