Merrivius Elf and Human Comics - Don't you forget about me Elf

Reminds me a bit of Mommy Fortuna from The Last Unicorn. She's a witch who trolled the shit out of an immortal harpy that never forgets under the assumption that it would one day take its revenge and end her. She would then live in its head for eternity, considering this to be a form of immortality.

That's basically Frieren's plot, isn't it?