on one condition...

You can't believe how well this is working! You decide to see how far you can push it.

 "Not a bad start, but there's something else you should do when your asking for something like that."

  She looks confused as you undo the tie that's keeping her propped up, but are careful not to untie her hands. You **** her to her knees and unzip your pants. She has a look that's a combination of longing and shock as you slap your cock against her face. Your a little surprised at it's increase in size, and you wonder if she's actually going to be able to fit it in her mouth.

  "Suck it, and I'll let you cum."

  "Mater that's disgusting! Your my brother!"

  "Are you really that concerned with that kind of thing when you can't bring yourself to call me anything but master? How long can you stand the burning in your slutty pussy? This is who you really are."

  You can tell she's still hesitant, so you put it in her mind that she loves the smell as you rub your cock on her face. You also add in a craving for your cum. As she takes a deep breath you can feel her mind going blank.

  She slowly sticks her tongue out and runs it over the shaft. She takes the tip in her mouth and begins to lick and suck on it.

  "Take it deeper"

  She struggles to get it in her mouth, but manages to fit her jaw around you. She seems to be aware of her teeth, and is careful not to let them come to close. She keeps twirling her tongue around the shaft as she starts bobbing back and forth. She's unskilled, but she's frantically trying to get you off so she can cum.

  "See how hard your trying? I told you. This is who you are. Your a pervert, and you were born to be my pet."

  You can see her blush more deeply. She's clearly humiliated, loving it, and hating herself. After a few minutes it becomes obvious that her unskilled tongue isn't going to get you off. You decide to help her out a bit...