The alt history setting is a response to Student Transfer (a body swap visual novel I used to help make) having its own "San Fransokyo" setting it never explains and me vowing to not do that myself. It (the Stephen King novel) was a partial inspiration in that the main character is secretly the town itself through the unbelievably rich and detailed history that is told throughout the story that keeps changing perspective and time frames. I can't say I've matched King during his 80's cocaine bender, but I have done that to a smaller scale, much of which isn't visible to the average reader. I swear it is in fact really important that this setting is the way it is, but it's for reasons I can't explain without ungodly massive spoilers.
Samantha is probably my favorite character to write as I get to be clever through her. Her character is at least partly inspired by the dramatic awfulness of my own mother, but dialed up to 12 and made more sympathetic with the possibility of a redemption arc. But just as I say with Z, they need to work to earn their happy ending, and that must come with a recognition of all of her own flaws.