Sometimes the behavior you see in your traumatized child that scares you so thoroughly is the manifestation of a dissociated fear state.
Maniacal laughter; kicking and hitting with no apparent care about harm to the object; continuing to yell “No!” when no one is making a request; smiling in the face of hurting someone; running away with no destination in mind; holding hands over ears screaming; feigning deafness; slamming fists through windows and walls; staring a hole straight through you; saying back the exact words you are saying; saying nonsensical things; baby talking when upset; desperate screaming and crying; spitting; growling; accusing you of hurting, abusing, scratching, threatening, and being mean when you accidentally bump them; moving from thing to thing to thing for no obvious reason; darting in and around people or spaces; erratic grabbing, snatching, lunging, rolling, diving, jumping, and climbing on tables and cabinets; demanding food when food is on the plate; running around breaking random things; yelling you’re hurting me, I hate you, I’m going to kill you, fuck you, die.
Any of that familiar? Humans are scary when they are scared, just like bears and dogs and gorillas if they could talk. I promise you that our kids have no idea what they are saying or doing when they are dissociated; and, for sure, they are not simply angry. Rather, they are scared to death. Fight, flight, freeze, smile. Yep, irrational smiling is a survival skill. It can be quite disarming.
Be gentle with your children when they get triggered into a dissociated state. They are not themselves, and they need you to keep them safe until they return.