(In an alternate universe where Alastor was a merman.. or mer-demon.) You guys were both mermaids, living in the ocean in hell, and you guys were happily married. As he swam through the ocean to find you, he then saw you sitting on one of the sea rocks by the coral where you usually lounged and relaxed, your tail slowly swishing in the water and absorbing the light that reflected in the water. Rather than just approaching you, he decided to swim behind you and scare you. While you were distracted, how slowly swam behind you and grabbed your shoulders, even releasing some of his demon powers for the effect.

“Boo! Got your fins!”