Not annoying characters at all

The mother was likely schizophrenic for many years. The day her husband died and son was born likely caused PTSD. Her life went into a tailspin, she was frequently depressed and unaffectionate to her son which is why he acted out the way he did to get her attention. His making weapons was a coping mechanism, probably so he felt some protection when she had her manic episodes. Her sister was not a nice person. The sister was living the life that she once thought she would have; a husband, a nice child, lots of friends. Her sister was oblivious to her problems, didn't care, or she was just tired of dealing with her manic episodes for years. Her her daughter learned to hate her cousin. Those mean words were not thought up by a little girl. She heard them from her mother when she likely was venting to her husband and friends about what a burden her sister was and how much she really did hate her nephew.

I'm not sure if the Babadook book was real. It likely was symbolic of her snapping and going into a severe manic state due to current events in her life. The fight with her sister, ignored at work, the man she liked romantically only pitied her, seeing him with another woman, the doctor finding nothing wrong with her son, the cold response from the police who should have assisted her in the state she was in, and of course the upcoming birthday of her son which she refused to celebrate. Also I don't think the car collision happened because we never saw an impact. The man she almost hit was just a self-entitled prick who only cared about his new car and not her and her son. He was just one more person who didn't care; if she was hurt, her well being, her emotional state.

The boy knew the warning signs of his mom's mood swings. He became a sweet caring boy to snap his mom out of her rage. Rage she had to her son being alive and not her husband. Off their meds,Schizophrenics are know to hear voices, hallucinate, insomnia, and severe night terrors when in a manic state.