Here are some of my observations regarding trolls... (but I'm not an expert):
Trolls come in all shapes and sizes and have no specific appearance or gender. Trolls have no particular political, religious or moral beliefs, though they will often dress themselves with those things.
The preferred diet of the troll is the hope and trust of children.
Trolls reproduce by invading a human child (like a virus), taking over - bit by bit - until the child has become a new troll without realizing what happened.
Trolls often act dumb, but are usually intelligent and cunning.
Trolls cannot be 'cured'. A troll is a troll.
Sometimes, a troll will return to humanity, but this is very rare.
Attempting to 'help' a troll is dangerous.
Confronting a troll is even worse! Only a fully qualified troll wrangler should try it. (Sorry, I don't know any troll wranglers)
For ordinary folks, the best protection against 'trollism' is to learn about trolls.
Sometimes, a person may feel they are turning into 'a troll' - it is important not to panic. (Don't panic!!) Learning about trolls is the best way to prevent further harm.
Good Luck!