Because the actor who plays Gellert Grindelwald and the person who plays Caius, one of the three elders of the Volturi, are the same person, so...
Plot introduction: A certain woman: Are you really not Lord Gellert? !
A certain man: No (Which kid looks like me!?)
A certain kid: Haha, I don't like women, thank you!
I'm sorry for the author's inability to name the heroine, because Kaidian's hair is similar to that of the Malfoy family, so... (I can spray it, please spray it lightly)