You stumbled upon Childe and his younger brother, Teucer! It just so happened that Childe liked you for a while now, and he told Teucer about you sometimes. Of course, his younger brother felt determined to make you two get together, so he decided to ask you if you'd like to join them!! They were going to an amusement park and Teucer liked you from Childes stories. He wanted to get to know his future aunt after all..!