"Please give it back now... I really have to get back to work." Brock's tone is unconvincing; not fearful, but a little desperate. He was clearly into the idea when it lead to an orgasm... but now that he had shot his load, he was realizing the price he had just paid. You have the upper hand, and you know it, however. "No, this is mine. I told you, this is a real man's dick. And I'm the man." The delivery guy looks up at you, his eyes a mixture of lust, regret, and defeat. You take your opportunity. "Come back tomorrow and we can talk about it then." He perks up a little at this. You tell Brock to give you his phone, and you enter your number and send yourself a text. "Call me whenever you get off work." You punctuate this thought with a pat on his firm, ample ass. He's fully dressed now, but even through the khaki shorts, the contact with his ass clearly excites you both. Brock disappears into the bathroom for a moment to clean himself up, then disappears out the front door.
You already know you have no intention of giving this dick back. In fact, you feel like things are just getting started with Brock. You like how highly he thinks of you, how he calls you "sir" and "Mr." even though you're probably almost the same age (all magic rings aside). But especially, you like how he brings out your dominant side too. You want to change him more, and you want to be there to see it. You're not fully sure the ring can change others without changing you, whether you can make swaps without being involved. But you have a feeling the answer is yes.
You have a whole day to think about which of Brock's features to change, but several possibilities run through your head. You could change his feet, make them even bigger than yours. There are probably people all over the world whose sizes go into the 20s. Your inherited foot fetish sends a feeling of pure electricity into your dick, making you hard despite your recent excitement. You could make him more submissive, even make him your boyfriend if you can switch stuff like that with the guy you're currently seeing. Or maybe try to test the limits of the ring, and see if you can think of something more unusual.
In any case, your middle-aged body is tired from the exertion. But you don't mind. You accept that there are some downsides to your new life. A small price to pay, as far as you're concerned. You are growing to like your softer stomach, your large veiny cock, your five-o-clock shadow, your monstrously large feet. Yes, you like everything a lot. You want to explore this new life, not go back to your old one. You fall asleep quickly, your hairy knuckles and palms resting on your sagging gut. You dream of tomorrow.
When you wake up...