When you wake up, you decide what change you want to try on Brock. Feet seem like an obvious choice for you, the thought of playing with Brock's feet as they change is practically intoxicating. You realise how drastically you're drawn to this fetish, and that it probably would have disgusted the old you. You promise yourself you'll fix these urges, but first you want to have some fun.
You thought about a lot of possibilities, but you decide that it would be best to try to figure out the limits of your magic ring. Trying to change features between species could be an interesting experiment. You decide on making Brock the proud owner of two fat, hairy, gorilla feet. you can't wait to see how he reacts. Gorilla feet seem fun; they'll work like hands, and they're about as close as you can get to human within the animal spectrum. You go to your local zoo's website, and find a picture of a healthy male Gorilla. With your plan decided, all you have to do is wait for Brock to call.
A few hours pass; you spend the time calling work, asking for more time off (they warn you that any more after this might have consequences). You use your new shoes to take a walk to the store. You pick up some extra groceries, taking special care to remember bananas. You want to have some fun with Brock later, the kind that comes after the main attraction. Tease him a little. When you get back, you even clean up a little. The place looks great, and before you know it, your phone rings. It's Brock. "H-Hello? Um, Mr. [name]? I'm done work in 15 minutes. Should I still come by?" You tell him yes, come right over, then hang up. You want to stay aloof and in control. It feels good. You shower and get dressed; just as you're pulling on your second sock, now fully clothed, your buzzer rings.
You answer the door, greeting the delivery boy for the second time in two days. This time however, his lithe frame isn't hidden by his uniform. He's wearing a tight v-neck shirt that showcases his strapping build. He's wearing tight-fitting Bermuda shorts; still khaki, but khaki that shows off his semi-erect cock (much less substantial than it was yesterday, of course). Brock's mop of brown hair is carefully styled, and the sun is catching it, making it look exceptionally shiny. You gesture inside. "Come on in, Brock." When the door is shut behind you, you grab your guest by the small of his back and pull him close. Your cocks, now both rock hard, bump together through your clothes. You press your lips into his, and let your tongue explore his mouth deeply. You can taste his mouthwash, cool and wet. It makes your tongue tingle a little. He looks, smells, and even tastes perfect. You can't wait to change that. You pull back. "So?" Brock says, eagerly. You shake your head firmly in response before he can ask. "Lay down on the bed. I want to take this slow."
You both strip down to your boxers. You gesture with an open hand towards the bed, and Brock lays down eagerly. The tight, neat comforter is ruffled by the pressure of this young stud. You lean over him to kiss him. You grab his boxers and pull, the springy elastic waistband giving easily. You toss the undershorts aside, and start to rub your hands all over his lean muscles. "Close your eyes," you tell Brock, "just focus on feeling good." Your hands travel across the young man's body. You catch yourself thinking of him as 'young' again, but it doesn't concern you. Even though you were his age only yesterday, you feel over 30. Inside and out. You continue to work your way down, punctuating your hands' circular pressure with kisses. You give careful care to caress each inch of him, and move your way down to his feet. You kiss them a few times, savoring the distantly sweaty smell behind the sharp, clean scent of body wash. They're smooth, like the rest of him, but the bottoms are calloused. Probably from all the running around for deliveries.
Making sure Brock's eyes are closed, you pull out the ring from the waistband of your boxers. You focus on the gorilla you saw earlier and the man in front of you, and try to concentrate on swapping their feet. You close your eyes and kiss the ring. Under your left palm, you feel the delivery boy's foot swell, the wild, newly grown fur. You discreetly remove the ring one-handed from your right index finger, and continue to rub Brock's feet as deeply as you can. You watch his face. It takes a moment for the blissful smile on the handsome man's face to change to a look of confusion, and finally his green eyes pop open. But his eyes aren't drawn to his feet first. Brock is looking at something else, at the other change...