They are extremely argumentative and also hold onto grudges easily and won’t let anything go without a fight.
They’re extremely negative and critical all of the time and they never offer anything positive to a discussion. This also extends to them never being happy for you in any way. E.g., getting good grades at school or a job promotion at work.
Due to this constant negativity, you cannot speak to them because you know that they will response in this way, or feel that you are walking on egg shells around them because of their negativity.
They are verbally abusive. They’ll insult you, call you names, etc, etc. They’ll also belittle you, your hobbies and interests, as well as friends and family. They’ll also use offensive language to that effect, e.g., calling your (actually decent) car a piece of junk or calling your friend a loser.
They are prone to physical violence.
They lack empathy towards other people.
Almost every time you would spend time with them or otherwise communicate like a phone call or a text message, there would always be some kind of agenda or ulterior motive behind it, because they want something from you and not to have a “normal” conversation.
They view you as a punching bag. Meaning that if they’re having a bad day for whatever reason that had absolutely nothing to do with you, they’ll lash out at you regardless.
They outright refuse to help you in absolutely any way whatsoever, even in difficult times. E.g., you are looking to buy a car or a house, they’ll refuse to help you. Or if they do choose to help you, they want something in return.
They do not respect your privacy. They’ll repeatedly barge into your room, demand to know who you are phoning, etc.
They are never, ever wrong and refuse to ever apologise for anything. They think they can sweep their behaviour under the rug and act like nothing happened.
They might also give you the silent treatment and ignore you for prolonged periods of time without explanation. And then out of the blue they’ll start speaking to you again like nothing happened.
When other people criticise you, they won’t defend or support you in any way. In fact, they’ll likely take the side of the other person criticising you.
They put conditions on their love towards you and having a relationship with you. I.e., do X or do Y, and only then will they be willing to spend time with you, etc.
They threaten cruel and unusual punishments for the smallest mistake or infraction. E.g., no meals for a week or locking you in your room for days like a prisoner. This might also extend to threatening to kick you out of the house and disown you completely as well for really minor things too.
They view you as a burden. They would avoid spending time with you if they could. You are made to feel that you should be grateful that they are “allowing” you to live in their home and having your other physical needs (food, clothes, etc) met when they could easily kick you out onto the street at a moment’s notice.
They are prone to wild mood swings. One moment they’ll appear to be “fine” and in a good mood, next moment they’re angry and abusive. You never know what kind of mood they will be in on a given day. They get annoyed and angry at the smallest thing and saying the “wrong” would instantly change their mood for the worse.
Whenever they are harassing you with any kind of abuse (whether physical or verbal, etc) and you plainly ask/tell them to stop, they’ll ignore you and continue regardless. Either they lack the genuine empathy, or they just don’t care in the slightest about the harm that they cause others.
When you attempt to address a legitimate grievance with them or otherwise confront them about their behaviour towards you, they’ll attempt to invalidate your feelings and justify their behaviour towards you.
They accuse you of poor character or are otherwise very accusatory. E.g., when you are looking for a job, they’re calling you lazy or saying that you “have a bad attitude” and you don’t want to work. However, these accusations would very often be completely unfounded and it’s just an extension of their abuse.
They view parenting as simply providing the physical needs of the child, i.e., providing a roof over their head and feeding and clothing the child. But caring about the child’s happiness and mental wellbeing? Not a concern for them.
In the case of divorced parents; parental alienation. Meaning that one parent will constantly badmouth the other parent and otherwise make no secret of their hatred of them in an attempt to turn the child against said parent.