Punish her insolence 

"I really wouldn't push my buttons if I were in your position..." he teases her as his hand slowly slides on the thin fabric of the swimsuit from her belly up to her boobs where he stops and squeezes lightly, making her struggle against her bonds in reaction to his probing, as if to remind her just how helpless she was and that he was in control.

As he realizes that the boner in his pants was starting to get unconformable he lets go of her and turns around to leave the room. He didn't want to go too fast, he wanted to appreciate every second of this, and not go straight to the conclusion.

Unfortunately for the captive her relief was only temporary, before she could even bring herself together from the last **** he inflicted upon her, he was already back. She hears what sounded like a water bucket on the ground and the sight of a towel in his hands confirmed her assumption, and she knew exactly what was going to happen.

Several times during their online conversations they had talked about waterboarding as a **** method and they even joked about trying it on each other, as a challenge, if they ever met, they had seen people in Youtube doing it to their consenting friends and such. But this was a whole another ordeal, she was tied up, she was away from anyone who could possibly rescue her, there was nothing to do to protect herself and she had to count on his mercy and empathy, which he probably had a lack of or else she wouldn't be there in the first place. It was terrifying but she knew she had to calm down as much as possible if she wanted to stand any chance to survive this, or minimize her suffering as much as she could.

She barely has the time to take a deep breath when the towel suddenly lands on her face and blocks her vision, and immediately the water starts falling right on top of her mouth and nose. Quickly her nostrils end up filled with water and her body's reflexes make her attempt to get up repeatedly only to be defeated by her bonds, she twitched pointlessly, while the urge to inhale air was getting harder and harder to resist. Her head turned right and left as to avoid some of the water and attempt to inhale some air, which Anthony only picked on by the time the first water bucket was empty.

She hears his footsteps as he leaves the room again with the empty container, the towel still on her face lets her know he's coming back with more. His silence during all this time added with her anxiety from what she just had been through and not seeing anything under the towel made her feel like he was probably really angry at her, and it made everything so much more terrifying, her heart was pounding so fast that it made her feel dizzy.

From the room where he went back to refill the water bucket, Anthony could still hear her panting, coughing and blowing her nose. It was basically a room turned into a bathroom for basic needs in the dungeon, it had that old "squatting toilets" system that consisted of a hole in the ground, and a tap in the wall. He made sure to let the water slowly fill the container so she could hear it as a way to let the tension and anxiety build up inside of her, only to make everything a bit worse.