Humans are inherently social animals, and within the complex social networks, there's a tacit understanding among each other to maintain relationships, exchange resources, and achieve goals.
No matter which country or world, as long as the concept of "society" hasn't completely disappeared, or developed to some extreme level... human interactions will always exist.
The same applies to the Aifala Continent.
Baron Farrow is the sponsor of Hai Yin's work in the Coral Association, funding that has saved her a lot of trouble; and Hai Yin's identity as a professional spellcaster made the baron see potential in her, investing early with the hope of reaping returns later.
Thus, from this back and forth, the so-called "human interactions" are born.
Baron Farrow would occasionally spend money to hire the adventurer crew Hai Yin belonged to for a round of drinks; during mission intervals, Hai Yin would bring some rare little things encountered during her adventures as gifts for Miss Ai Li.
