>

highly recommend the books   
"The Body Keeps the Score"
but also "Complex PTSD: From Surviving to Thriving"  
Because complex trauma is absolutely a thing that is recognized from the mental health community, but isn't yet in the DSM. It's trauma that is from sustained abuse as opposed to trauma from a single incident such as a car accident or a suicide.
I worked in Psych for a number of years and we once had a patient who shot and killed her husband. She had all charges dropped because her husband had been beating her for 20+ years. Interestingly enough, she was one of the nicest individuals that I've ever met. >

Probably super nice bc she knew what a total ass can do. So decided to be the opposite. >

Might be a defence mechanism. 
If you’re nice and accommodating you might feel like it’s less likely someone will hurt you. >

It's a classic trauma response.  We all know about "fight or flight", but there's also the "freeze" and "fawn" responses.  The "fawn" response is a common one with abuse victims, especially child abuse - they just do whatever they can to placate the abuser.  They say whatever they can to make it stop.  They try to be as pliable and submissive as possible to not be a target of the abuser's rage. >

I've worked in mental health for over a decade and never heard of this. It makes SO MUCH SENSE and wish this was talked about more. Thanks for sharing.