Okay okay okay idea for a Wicked/Oz books AU, except famous 40 addition going off of this post.
So Nessarose dies, but ends up in Black Forest and this colorless domian as her afterlife. She spends years there, just trapped and hunted by the conscious animals there and basically being tormented by the place. (Not trying to veer into the idea of Hell and Heaven much but it does feel like a place she was put in as a punishment for some years).
But over time she begins to learn. She learns there is magic here she can harness, and slowly does so. Sparking the first bits of color ever seen in that domain with that magic.
She has changed in this time, but only so much. It still takes years but eventually she becomes a witch fully in her own right and has taken over and become the ruler of the Black Forest. It is due to her magic the place eventually comes to stand in a place in Oz between life and death. When she becomes known again, she does take on a new name.
An idea I think many stories can go off of, giving Nessarose that power, the idea with Tin Man said above in a Wicked form because of course she didn't lose that, as well as her encountering a wondering Scarecrow and Elphaba (Maybe as a reincarnated Scraps? Since this is pretty deep into Oz lore) searching for refuge, among many other ideas.
