My brother is a sufferer of human-variant MMS. It's a genetic condition. Faced with stressful situations, his body reacts by changing to blend in with its surroundings, like a chameleon changing colour to camouflage itself. It’s instinctive, uncontrollable, and his body hold him in that shape until the threat is sensed to have passed.

Naturally, dating is never easy for MMS sufferers. One minute you’re one person, the next you’re somebody else entirely. My brother David has had several girlfriends but they never last. It all goes awry at the point of intimacy, the elevated heart rate triggering the change. He just can’t help it. He told me a story of one time, while visiting his girlfriend’s family, he actually turned into a doppelganger of her mother when she touched his leg under the dinner table. Worse, his persona changes too. So there he was berating his ‘daughter’ at her choice of date.

“There’s this totally hot girl at college. She wants to hang out with me and her friends at the water park. It's kindof a date. Any chance you could tag along?” he asked.

“There’s not much I can do if you change, bro,” I reply.

“I know. It’s just for moral support. Whatever stops my stressing out, right?”

“Sure. Just be sure to fix me up with one of her friends.”

So there I was, third wheeling his date at his bequest. He wasn’t wrong - he’d picked a stunner. Against her amorous advances, it was obvious my bro was struggling to keep himself under control, both his condition and the excitement in his swimming trunks. When she leaned in for a kiss, it overwhelmed him. His locked lips gave a quiet mewl of despair as the MMS changes overcame him, his hairy torso rippling and crunching down into a feminine hourglass. By the time their lips parted, he was no longer David. His black trunks shifted accordingly, sliding up over his feminized torso to encase his breasts, though not in time to conceal the spectacular tits.

I took stock of the girls around us - Sarah and her four friends. David’s MMS had done the same, analysed and merged the five teenagers into an amalgam. If you looked close enough, you could make out individual features - Megan’s breasts, Sarah’s eyes… His reflex was blending him into the surroundings perfectly with a persona to match.

His wide eyes had that familiar blank expression. For a few moments after the change, there was nothing inside that head of his until the new identity found itself to tether itself to. He tugged

vacantly at the spandex “Like, what am I doing here?” he asked, his voice air-headed and simple.

“So this is his condition, huh?” Sarah says. “Don’t you remember? You’re here on a date.”

His eyes fixed mine with an intense gaze of understanding. “Of course I am,” he murmured as the persona established and locked in. “Here on a date with my hunky boyfriend.”

“Wait, I’m not…” His body moved with a fluid, feminine grace as he waded across the pool. It was too late for me to escape, he’d already snuggled his spandex-clad ass into my lap, wrapping his arms round my neck and pressing his lips to mine.

I know I shouldn’t have. I know I was taking advantage of him in a vulnerable state. Anyone could have filled that empty head with whatever lies they wanted. I could have made him think he was my wife if I wanted to. There was no way he could realistically consent like this.

But I’m just a man. And as his ass ground eagerly against my cock, my willpower gave out. I kissed back, exploring, groping his nubile flesh. The thought of fucking not him but Sarah and her friends all at once tantalised me. My hand dipped below the water, pressing against the crotch of his swimsuit to examine his tight, hot slit.

“Clearly I’m not needed,” Sarah’s voice sighed dryly as she climbed out of the pool. “I’ll leave you two to enjoy your date.”

Her words faded into the background as David's body filled my senses. Tugging aside the swimming costume, I enter him.