Dumbledore's secrets
She was a Gryffindor and true to her House she was one of the bravest witches of her time. It took great deal of bravery to fight the one Who-Must-Not-Be-Named, but even harder was sometimes do something what didn't feel right, but a man who liked keeping secrets was saying otherwise.
"Are you sure it is wise, Albus?"
"I thought you once almost liked the boy."
"Yes. He was different than others Slytherins – he was a friend of Lily Evans despite the fact that she was muggle-born and also Gryffindor. But in later years he changed. He liked too much Dark Arts and in these times..."
"Do you think I would endanger students of Hogwarts by appointing Lord Voldemort's faithful servant as a teacher?"
Minerva flinched when hearing the feared name, but then she composed herself. "No, I don't think so. But you sometimes put too much trust to wrong type of..."
But Dumbledore interrupted her. "Great, then all is settled, isn't it? Would you be so kind and show and explain everything to Professor Snape when he arrives? Thank you."
What else could she do than say: "As you wish, Headmaster," and then just wait for new professor's arrival?