You give Kat just enough time to lower her guard as begins walking down the street, then mustering all your mental power, you force her breasts to bloat out in one swift explosion of size. Kat moans loudly and falls to her knees as the sensation overtakes her, causing several passerby to stare.
“You... you’ve got to stop doing that...” she pants, doing her best to regain her composure. Her engorged breasts are still bouncing, and you giggle inwardly that you didn’t even have to make them. “I own these now,” you think to yourself with satisfaction. You’re going to have a blast doing everything in your power to make your sister’s curse backfire.
With a pout on her face, Kat looks around blushing and taps her chest with her wand, making her mammaries shrink back to normal size. “Seriously, stop it!” She hisses down at you. “I don’t know how you’re doing that, but I’m checking my spellbook as soon as we get home, and I’ll make sure you won’t give me any more problems after that!” In a huff, she gets back to her feet and starts walking again. You silently consider your next move as she makes her way across town. What else can you do in this form? It still feels pretty nice being a bra. Your human senses are gone, but you can still feel Kat’s breasts under your grip slightly, almost as if they’re nestled in your hands. You try to nuzzle your face against them, but all it translates to is a gentle swaying of her breasts back and forth. She doesn’t even seem to notice, as she’s focusing on boarding a bus. This gives you an idea.