The last items for Betty and Blake are a bit tricky. Not like every other item in the game, you don't have to destroy the uman part on the slittherhead for unlock them. I recommend to try to unlock it after you have the victim counter.

- For Blake, you need to finish the mission "Black Payback REV (Mirror)" with 0 casualities. No specifics Rarity needed. I make it with Edo as teammates.
- For Betty, you need to finish the mission "Bind Break" with 25 or less casualties. No specifics Rarity nedded. But you need to be fast and have a good RNG cause the Slittherhead can kill some civilians while running and keep killing civilians when you are not with him.

Now you can have all the costumes for your Rarity, be a Fashion Victim and have all the achievement in the game. Enjoy your victory :)