10 Behind The Scenes Reasons For Harry Potter Character Traits
2. Barty Crouch Jr.'s Tongue Flick
David Tennant played Barty Crouch Jr. in Goblet of Fire, and decided to give the character a strange tic - a tongue flick which wasn't mentioned in the Harry Potter books.
The infamous tongue flick was actually thought up by Tennant himself in order to add some unhinged flavour to the character, at which point director Mike Newell realised that Brendan Gleeson would also have to perform the same move while playing "Mad-Eye" Moody, who is impersonated by Crouch using Polyjuice Potion.
The tongue flick is a minor fiasco among Potter fans, some seeing it as a needless affectation and one that made Crouch's impersonation of Mad-Eye too obvious for those who hadn't read the books.