10 Crazy In-Universe Rules MCU Characters Must Follow

Perhaps no Avenger has had a more devastating backstory than Black Widow (Scarlett Johansson), who reveals in Avengers: Age of Ultron that as part of her training to become a Black Widow assassin, she was sterilised before graduating.

Natasha says that it's "efficient" and "one less thing to worry about," though it's clear that she was left hugely traumatised by both the sterilisation and her general experiences being trained as a Widow.

This is further explored in her solo movie, where her adoptive sister Yelena (Florence Pugh) graphically explains to their father figure Alexei (David Harbour) what the involuntary hysterectomy procedure entails.

As if transforming orphan girls into elite assassins wasn't sinister enough, removing their reproductive options in order to make them more pliable and less of a flight risk is just seven shades of f**ked up.

Considering the callousness of Red Room leader General Dreykov (Ray Winstone), it's safe to assume that any Widow who rejected the procedure would've either been disposed of or, once mind control measures were instituted following Natasha's escape, simply made to submit to it.