In conversation, Hagrid said
"first thing you wanna know about hippogriffs is that they are very proud creatures.
you do not want to insult a hippogriff."
I think nobody said to him like "i want to know about hippogriffs" and there are no Nonverbal expression of that meaning.
Why he use "you wanna know"? Isn't it more reasonable to use "you gotta know"?
And, "you do not want to insult a hippogriff" means "you should not insult a hippogriff"?(a warning?)
If I think right, Why they use wanna and want for warning or teaching?