Stud to a school of mermaids! Damn, it's every man's fantasy!
They feed you a potion and you rapidly change into a very verile merman. A dark beard covers your cheeks, chin and upper lip and your upper body blooms in muscle. Dark curly chest hair spreads over your stomach and pecs.
Your cock grows long and recedes into a pouch like a dolphin's. In fact, merfolk aren't apparently half fish, they're half dolphin. Your mind reels as you change. You accept your new form and your new duties as a stud merman.
One of the females hands you a trident.
You are now the Alpha male, consort and King to our Queen we will take you to our Queen and you will learn more of your duties and responsibilities.