beaver is a mask

I was almost confused in the middle part when the beaver is on control. I thought the movie is about just let the past go,
don't stop yourself by the past.
But at the ending,
I think ...the movie is trying to tell us a very simple thing,
be real to yourself.
No matter the past or the future,
something just can't hide from.
Son trys to not be like his father,
father trys to not be like grandfather,
girl trys to pretend that she's fine...truth is she's not fine.
Everybody has the dark side, you are not alone.