Yes, well, Lucy has very deliberately not used her power in front of Gabriel. Well, not that she's had cause to, anyway. She knows she can't use it (effectively) against him, as he'd remember what happened anyway, and there hasn't been any reason for her to use it for him. She also generally prefers not to use it against people she actually knows. It doesn't seem right.

"Do you really not want your power back?" she asks Peter. "If you were able to control it, that is."