Talk:Soushin/@comment-45737981-20200726012629/@comment-11883116-20200726034400

Aside from what's mentioned in fanon, pretty sure it's because of their similarities in both appearance and personality (although it's debatable how much of it was Shin's act in case someone else in the group knew Shin) so being Foil characters to each other, having a past history with each other, and a trope called Foe Yay.