1. Nagini was a human IRL before becoming Voldemort's trusted pet.
The Potterverse lost its damn mind when the final trailer revealed Nagini (Claudia Kim) — the last horcrux and Voldemort's pet snake — was actually a human. The reveal confirmed an existing major fan theory. Rowling later clarified on Twitter that Nagini was a Maledictus, or someone who can morph into an animal because of a blood curse. (This is not to be confused with with an Animagus, like Professor McGonagall, who can control their transformations.) Rowling also revealed she's been holding on to Nagini's secret for about twenty years.