There are many kinds of immortality. Not all forms are equal. The Sea Slug Witch's immortality, to many, may seem like a lesser kind, but it has a certain beauty to it.
You see, The Sea Slug Witch never dies. But, at the same time, it was time for Sea Slug Witch to pass on.
She had already made her preparations. It is not uncommon for a Witch with a lesser immortality to seek a greater one. She had hand picked her favorite dolls, packed all of her most personal things, and supplied herself with a subset of the Sea Slug Witch's most powerful magical reagents. She was sure she could pull off some kind of reincarnation- or at least bargain an entry into one of the nicer afterlifes.
But before all of that, there is unfinished business to attend to.
The Sea Slug Witch flies past the lush faewoods, a wild, free, and safe haven for witches like her. She flies over the wildwoods, the boundary between magical and mundane. She flies past the pastoral villages and suburb limits, where she would usually recruit her dolls. She flies past the cities she would visit when she felt particularly adventurous. Instead, she flies to a blighted place- the inner heart of a cruel empire- a hell with the gall to claim itself heaven.
She'd never dare come to a place like this, but her immortality is special. It doesn't matter what past Sea Slug Witch chose to do, she has a moral obligation.
She finds someone alone, in the dark alleys. Someone whose soul hungers. Someone failed by their family, nation, and even body. Someone without attachment to their empire. Someone who sees the smoggy air and callous buildings for what they are. Someone who wants a second chance.
It is dangerous for the Sea Slug Witch to fly so low. Dangerous to approach this stranger. Dangerous to hold them, lovingly. But it'll only be a moment.
The Sea Slug Witch shows the stranger what it's like to have the hands of a celebrated witch. Hands soft enough to reassure a scared doll- deft enough weave both clothes and runes. Hands that know how to take things it wants- even secret, forbidden things like the hearts of girls or the creeds of long-forgotten gods. The stranger learns these things, for now they too have the hands of the Sea Slug Witch.
The Sea Slug Witch continues through her body. She shows this stranger all of the benefits associated with her title. Arms, strong enough push back against the world. An all-consuming gut, used to bountiful feasts but able to withstand even the vilest poisons. Legs, both beautiful and functional. Sensitive assets, to share with the most treasured people. A tongue, with silver charm. Eyes to see secrets. A mind to recall- you are the Sea Slug Witch.
And with that, it is done. The world doesn't need two Sea Slug Witches, but it must tolerate two in the interim. The XXIIIth Sea Slug Witch leaves her successor some privacy to sort things out.
The old Sea Slug Witch tails her double just long enough to watch her fly out of the dangerous territory of the empire. The new witch darts straight to her manor in the faewoods. Sure, a few close contacts, a few lovers, maybe a few rivals and a handful of dolls know the secret of the Sea Slug Witch. But for many, many others- they'll be happy to see Mistress return, an old business partner end her vacation, or an old flame become active again.
As for the old Sea Slug Witch? She heads to her secret hideout. This body of hers, it'll hold out well for another few years, and might be able to struggle for life for another decade if she's lucky. However, she already has grand plans for her next life.