Headcannon:
Character A develops a nickname for character B upon meeting them, and no one else calls them that (bonus points if character B hates the name)
And then in a heat of the moment scene, where the big boss is about the be revealed, and character B is like kidnapped and tied to a chair, they hear a smirking voice behind them, “hello (insert unique nickname)” and character B is in disbelief because only one person calls them that but they just *cant* be the leader right?