“Okay,” Kat mutters under her breath, gasping for air as you pleasure her chest. “You think you’re awfully smart, huh? I know how to fix you...” Your sister staggers forward, adjusting herself to the new weight on her chest, then flicks her wand as soon as she regains her balance. You feel a momentary yank, as if you’ve been pulled backwards. You’re confused for a moment as you try to make sense of what you’re seeing, somehow in your mind’s eye you can see out at the busy street in front of your house, and the continued tightness of Kat’s massive breasts inside you. However the front of your house is also fading into view, and a separate tightness is filling some other, different you at the same time.
Kat speaks up before you can figure out what’s going on. “There, that should make you too weak to mess with me any further,” she whispers down at her tits. You try to look up at her, but your view of the house shifts instead. “I’ve split your mind between my bra and panties, so your willpower will be split by half. Go ahead and try to ruin my birthday now, twerp.”
As you slowly make sense of inhabiting two bodies at once, you can make out the small crowd that’s gathered around your sister. Some are talking amongst themselves, others staring silently. “Ugh.... now I have to figure out how to wipe all these memories...” Kat groans to herself. “Where did I leave the spell book?”