Makes sense why the dragons have to go, sure the current ones are chill, but they're not always gonna be alive and in-charge and all it takes is one bad leader and all the humans there get massacred.
Autists don't realise trauma doesn't have to make perfect sense, something bad happened to him when he was younger and it got ingrained into his psyche, simple as.
She on the other hand just has zero sense of empathy since she doesn't seem to care how her actions might affect other people or...