Technically that would be called a selkie 🤓

But slay, I'd imagine it would be similar to Song of the Sea, with either Mama or Vati being a selkie and choosing to live on land for one reason or another and hiding their pelt. Fritz would either find out willingly or on accident, drive into the beach, tries on the fur coat and inmediately turns into a leopard seal

AND HOLD UP I JUST LITERALLY THOUGHT ABOUT THIS AS I WAS WRITING THIS. Leopard seals not only are big, but are one of the only registered to have killed humans. Seal Fritz finds a late beach goer, and since they disturb him on instinct he attacks. When he's come back to his senses he's sick to his stomach, thinking he's nothing but a monster...