Summoner: Recognize Kain as the big brother at the beginning

Yuxi traveled across the King's Continent with the (King's Summoner System) and met Kain, who had just left the family, at the beginning. However, as the plot developed, things seemed to be getting more and more wrong. In the early stage, "Big Brother", "Yeah", in the middle stage, "Ah Kai~", "Hey", in the late stage, "Dear ∽", "I'm here", in the late stage, the MC said, "Let's congratulate the two newlyweds and get married." Yuxi fell into Kai's arms with a happy face. "Oh my god!" (Not purely original, written for practice)...