I can't tell if it's care or just pity. He looked pained when he broke her legs, he looked pained when she said she wanted to go out, he looked pained when he was ordered to kill her of he had to... He could just have a hard time to do these things to a charming and innocent girl.
And yeah, being overprotective is his job anyway.
I kinda do. He did seem to care for her, and not just because of the job. I think over time he really began to care, but this manga loves to play the heart strings, so I don't know.
Anyone else want Wolfram and Sulivan to have a happy ending together? He genuinely cared for her, so I hope he gets time to explain himself.