In the scene from the Deathly Hallows when Hermione pretends to be Bellatrix
Before shooting, Emma Watson acted out the scene, so Helena Bonham Carter could mimic her facial expressions during the actual filming.
This scene is Helena Bonham Carter,
pretending to be Emma Watson,
pretending to be Helena Bonham Carter,
pretending to be Hermione,
pretending to be Bellatrix.
ITS MY MY FUCKING BIRTHDAY