Canon question (DH)...
Snape is refusing, telling Dumbledore that the Dark Lord is gone for good and that Harry does not need protection.
Dumbledore tells Snape, instead, that Voldy will be back.
Question:How does Dumbledore know that Voldy is not defeated for good?
It can't be the prophecy that Dumbledore heard, b/c Snape eaves-dropped on it and he is not convinced that Voldy is coming back.