Angus swallows the last of his wife's potion. A second later, he is crouched in the hay, struggling to hold on to the contents of his stomach, while his body tries to violently reject it, sensing the danger in the unnatural, mutagenic liquid. A hot, painful churning builds in his abdomen as if his intestines are moving like living worms. With torturous slowness, the pain spreads out across his chest and limbs.
"I thought it'd be quicker than this," he groans between dry heaves. "This is agony."
His witch of a wife clucks her tongue. "This is fast," she explains with a huff. "Did you expect me to just wave a magic wand and poof—horse? Replacing every cell in your body takes time. Even magic has its limitations."
His skin grows tight as equine muscles bulge beneath. The skin of his hand flows, making his fingers first webbed and then fused altogether, as his fingernails merge and spread into dark keratin. He casts a glance behind and sees his feet are far ahead as black hooves tear their way from his boots. The seat of his pants swells about his growing tail before bursting open.
The sensation of his squirming organs is somehow worse than the pain itself. He feels his bladder politely make room for his burgeoning uterus, the large fertile womb of a young mare ready for breeding, which shoves aside his human organs in its aggressive development.
He focuses only on the goal. After several bad harvests, his farm was bankrupt, while the neighboring ranch, specialized in animal breeding, made money hand over fist. In desperation, he did what he'd always hoped to avoid, as a staid, level-headed farmer, —he'd turned to his wife's magic, thinking that she might have some weather charm in that tome of hers. She formulates a different plan, quite literally, as she sets to work mixing mandrake root with mare's hair.
"We'll sell you as breeding stock," she'd explained excitedly. "They're desperate for new mares after their new prize stallion, well, got them all pregnant! You must have seen it - that beast must be worth a fortune, not to mention its *ahem* white gold. Just think, we get to fleece them two different ways. First, they pay for you. Then, once you're bedded down beside their stud, you slip out of your stable and lead him back here across the fields."
"You want me to seduce a horse?" he spluttered.
"If I make this potion right -and if the creature's reputation with the females is to be believed- it shouldn't be hard," she giggled. "Just bat your eyes at him, flick your tail, or whatever else it is horses do when they're in the mood. Once you'd led it home, I'll feed you the reversion potion and we'll bed him down with our mares for the night. Even if his owners take him back, we'll still have his priceless, prize-winning foals growing inside them by the morning!"