She tries to rebel

"No!" she said, sternly. "I'm not your ****."

Erik didn't bat an eye. "Suit yourself." he told her.

Suddenly, the runes on Irina's thighs glowed incandescent and started to burn her. "What's going on?" she screamed.

"Didn't I tell you? How forgetful of me." he mocked her. "I can make the runes burn you if you disobey an order. Now, if I'm not mistaken, I remember telling you to do something."

"Yes, yes, I'm your ****, I'm your ****!" she screamed. "Just, please, make it stop!"

As the words left her mouth, the runes went back to their original state.

"That must have taken a lot of willpower, refusing to obey like you did, it was pretty impressive."Erik commented. "However, I hope this has thought you to never defy me."

"I'm your ****, I won't defy you again." the demon said, still in pain.

"Good, good. Now, let's see if you have indeed learned your lesson. Suck my dick: you have five minutes to make me cum."

The demon got to work, going as fast as she could.