Evil_Dragon
Mind control/hypnosis is great and all, but as a villain you shouldn't ever depend on it. It's like a castle made out of sand, one tough day and it'll all come crashing down.
That's why he only uses her as a information source nothing more. She literally has to behave as always. And she is just a catspaw ready to be discarded at any time.
Kido_TO:True I agree with you. Hypnosis and mind control can be broken easily sometimes.. I personally feel that making servants by placing soul mark(or what mc said I forgot) is more reliable