Yes and no. Lecter likes her, yes, but he is also nothing if not true to himself. He's a manipulator. To truly manipulate someone, you keep yourself unpredictable and arbitrary when it comes to being kind and being scary. It's a well-known tactic of abusers and manipulators. Show someone kindness and cordiality, then suddenly shift to anger or intimidation. It prevents them from getting truly comfortable around you and they also subconsciously crave your kind and cordial side again, thus making them more susceptible to wanting to please you.