HP: What Can I Do If I Travel and Become Grindelwald's Sister?

Lin Yinnian originally thought that he was lucky enough to be able to travel to the HP world that he had longed for, but when he turned around, he saw his cute brother Gellert, who was two years younger than him. Touching his head triggered a cheating system. Tuan Fa Xiang, an otome novel, without a male protagonist. Purpose: I really like HP fanfics, but the big guys are so slow to update, and the newbies are writing their own works.