Foot fetish

They put the girls into trance.

"Girls," Willa said. "You all have a massive foot fetish. You love sniffing, massaging, and licking anyone's feet. The sweatier and smellier the better. You will beg your sisters to let you sniff their feet after a workout, as well as sniff their socks and shoes."

"Except for you," Persephone pointed to the sole brunette. "You are going to be me and Willa's personal foot slave. You love sniffing, massaging, and licking our feet, and only our feet. Any other feet make you retch. Understand?"

The three nodded. Willa and Persephone decided to take their new foot slave to their dorm for a test, and woke them.