Makes her think he's the owner of the house, she his obedient maid.

"When Natsu Dragneel knocks on the door of Mirajane Strauss's house, she will answer it in her maid outfit. Upon seeing him, she will forget she owns the house, thinking he does for the duration of his stay, and that she is his obedient maid. Pleasing him, especially sexually, will become her top priority, and she will greatly enjoy doing anything he says. Obedience to him is in fact her greatest joy, and she will be eager to receive orders from him.

"When he leaves, she will revert to normal, and think it was a voluntary roleplay, and will not regret it in the slightest." He shut the Note, walked to the door, and rapped his knuckles on it.

The door opened, and Mirajane said, "Yes, what is-" She froze as soon as she saw him, and it was as if a switch had been flipped in her mind. "Oh, you're back Master!" she said, putting on a smile full of joy and bending at the waist in a respectful bow before moving out of his way. He stepped in, and grinned at her.

"I see you kept the place in good shape," he teased.

"Of course Master, I live to serve!" Mirajane said, beaming and tilting her head. "Please, give me more orders..."