The next evening as Amber sat facing the camera on her knees, Master introduced the topic of His cum. His semen. The most precious thing to come out of His body. Amber's biggest gift, Master's biggest blessing for her. He told her nothing else mattered more to her than becoming worthy of receiving His cum. Because His cock was going to spend most of their time together in her mouth, her mouth would also naturally receive His cum the most. Amber was happy beyond words. Master said that for Him, a single drop of His cum was more precious than Amber's entire being, and as such she was to make absolutely sure she never let it go to waste. Master also told her the reasoning behind feeding her cum as much as possible. It would end up in her belly, where it would be broken down into nutrients and absorbed by every cell of her body, making her more His. There would always be His cum coursing through her body in one form or another at any given point of time. Amber felt like she wanted to drop down to the floor and kiss Master's feet for allowing her the highest of privileges.
Master said He fully trusted Amber would not miss a single drop of His cum, but He still had a very simple protocol designed to ensure His cum does not get wasted even unbeknownst to Amber.
Amber had never seen a live cock in person, and so Master told her it will be especially helpful for her. He said from the looks of it, her mouth was small, and knowing the size of His cock when fully erect, Amber would have a real struggle accommodating Him, let alone drinking all His rapidly spewing cum. He said just before He would cum into Amber's mouth, He would grab her by the hair, pull her mouth off His cock, turn her face up to His and slap her hard across her face, three quick slaps. Amber's heart was beating out of her chest reading all this.
Master said by the time He was ready to cum, Amber's face, mouth and jaw would be sore and achy. She would also be dazed from the intensely rough face and throat fucking. Withdrawing her mouth from His cock would give her a brief pause to breathe. That was important because there would be no way of telling when she'd be allowed to breathe again. Master would ride out His climax before allowing Amber to breathe again. Amber would fill her lungs as much as she could in the few precious seconds Master pulled her mouth off His cock just before cumming.
Looking up into His eyes would make sure her resolve to continue to please her Master despite all the pain and roughness becomes stronger. And finally the three slaps would wake her up from her trance, put her deeper into subspace and refocus her mind on the urgency of the task at hand: that Master was about to reach the throes of the greatest pleasure known to Him, and as His slave, she would do all she could to maximise Master's ultimate peaks of pleasure while making sure she caught every drop of His precious cum in her mouth and worked hard to help Him come down from His climax as pleasingly as she could.
She would not swallow His cum yet. When Master decided to withdraw her mouth from His cock, she would look up at Master and open her mouth wide to show His precious cum, His greatest gift to her. If Master was pleased with how she behaved while He used her mouth and throat, He would allow Amber to swallow His cum. Amber would thank Master for His cum that would be sitting in Amber's belly awaiting digestion, making her His all the more. After verbally thanking Master, Amber would bow down to the floor and kiss Master's feet. If Master happened to have his boots/shoes on, she would kiss His boots.