Yes, stay still

You hold onto your seat for dear life as your older sister massages your dick with her throat. Seemingly unconcerned with her own inability to breathe, she keeps you in there for a good 20 seconds, clearly intent on bringing you to your climax before you change your mind. Her impressive commitment to the cause of turning her face into a spunkhole for her brother's cock pays off as you lose control and orgasm with a low groan. She bottoms out and keeps her lips pressed against the base of your shaft as you explode, shooting string after string of your load directly into her stomach. To your surprise, your orgasm just keeps on going and going, the waves of pleasure continually rushing over you as rope after rope continues to fire down your barrel. Partly out of surprise and partly out of panic, you squeeze the muscle you would use to stop urinating mid-stream, and suddenly the orgasm just... stops. Conscious thought returns to you as the intense euphoria recedes, and Erika finally pulls her head back, allowing both your prick and her lungs to taste fresh air.

She gasps and splutters for a few seconds, unable to speak, and you start to feel bad, as if you're to blame for the state she's in. As you're trying to find the right words to apologize, she manages to speak up first.

"Aww, isn't there any more?" She sounds disappointed, almost concerned. "You usually give me way more than that. Are you feeling okay, John?"

"What do you mean? That was loads..." You are still coming down from your high, and the words come out breathlessly.

"Pfft, liar, I know what 'loads' from you feels like. I usually can't speak for minutes afterwards for fear of spilling some back up. Who are you saving your baby batter for, eh? Who's the lucky girl?" Erika eyes you jealously.

Once again you find yourself thinking back to Charles' words. "Basically men will be able to ejaculate several times what they could in your reality. They’ll be able to control the amount, whether that’s a teaspoon or a liter." He was completely right, it was really easy to stop the ejaculation as soon as you wanted. And if you only gave Erika a few tablespoons, you must still have almost a liter swimming around inside you, ready to fire out on demand. What wizardry! Finally, you reflect on the last thing he said to you. "Don't overthink things. It's that simple, you hear?" He's right, you shouldn't think about it too hard. If it's real to you, what's the difference between that and objective reality, as far as you're concerned? You didn't feel the need to work out how every little thing in the 'real' universe made sense, so why should you in this one.

"Nobody else, I'm just saving it for you for later." you find yourself saying. Erika seems satisfied with this response.

"Oh okay, I guess that makes sense. Just don't forget, you've promised me it's all mine." she sticks her tongue out and makes a cheeky face. "Now eat up your breakfast and get dressed so we can get to work."

Oh yes, work. How are you going to get away with not knowing what you do for work? You eat your breakfast timidly under the loving gaze of your two female family members. You'll just have to follow Erika and get her to lead the way.

After food, you go up to your room and get dressed into what you hope are work appropriate clothes - a smart shirt and clean jeans. Walking back downstairs, you pass your sister's bedroom, where the door is now open. Your eyes widen as you see the changes this reality has caused - the walls of the room are adorned by shelves, and each shelf is completely filled with giant sex toys, with a clear focus on anal toys. Metal plugs, glass plugs, rubber plugs, anal beads, rubber fists, enema kits, you name it, your sister has twelve within arm's reach. You can't bring yourself to explore further right now - you head back downstairs.

You bump into Erika, waiting by the front door, still wearing nothing but her tiny tube top and microskirt. She grins at you. "Ready to go make an honest living?"