Upon realizing she was failing Potions, and possibly wouldn’t be accepted into the Auror program, Nymphadora Tonks decided to do whatever she had to do sixth year to get her Potions NEWT.
Receiving the grade involved three things: her newfound ability to change her features to match a photograph, a picture of a young red-headed woman laughing, and Snape’s utter lack of remorse
The utter disgusting-ness of what she’s done makes her realize, six years into her Hogwarts career, that she really is a Hufflepuff after all - that she values hard work, patience, and honesty. That she should have valued them a little more before slipping behind a closed door with Snape, before letting him call her Lily, before learning things about the school’s worst teacher that she will never be able to unsee.
It’s after that unfortunate experience that she decides, NEWT or no NEWT…she’s going to earn her grade, and her spot as an Auror. Because she’s a Hufflepuff, goddammit. And Hufflepuffs don’t cheat for the grade.
@cpt-starlord - this is your fault.