Witch au but Sam looks far too much like Martha Wayne than a lot of people are comfortable with.
I hear you ask, "but Sam is younger than her in this au" and I tell you that Martha Wayne had the genetic trait of looking younger than she actually was, a trait that was in her family for generations.
Thus, we have Sam who resembles Martha Wayne far too much, the philosopher's stone that makes her immortal, and a genetic trait that has Martha looking younger than she actually is and you get misunderstandings.
So, Sam was just minding her business trying to figure out what exactly for her castle to be anywhere that wasn't Amity Park when someone stepped onto her property and, getting a feel for them she realized that they don't seem to be magical in nature.
Also, scratch that, it was more than one person.
So, she decided to give them a... 'warm' welcome.
A group of people who believed in the supernatural decided to get together one day to explore the castle that spawned randomly one day in Gotham for shits and giggles. So there they were, stepping through the fog, barely able to see the ground let alone each other.
They had to solve a puzzle for the door to the castle to open in those conditions, which was weird but it was also the fun kind of weird so they weren't complaining about it. When they opened the door it was very dark, which made them second guess themselves for a second and then they decided to step in anyway.
They live in Gotham what's the chances of this castle being worse than what they go through weekly?
The door slammed shut behind them as soon as the last person stepped inside, leaving them in total darkness for a moment before candles lit themselves up and they saw the inside of the castle in its full glory.
It looked, very, very beautiful.
So beautiful in fact, that they almost missed the woman stood at the top of the stairs. She looked very, very beautiful and was wearing a dress that looked very expensive (think Blue Diamond from Steven Universe but black) with a red gem right in the middle of her chest.
The lady welcomed them into her castle, and suddenly they found their vision going back as the woman's sinister chuckle echoed all around them and they found themselves in separate rooms of the house.
Fun fact, this group of people were also streamers and streaming everything up to the point of Sam's entrance and then her magicking them all in different rooms. They also had a pretty good following, so safe to say the chats were going crazy over what just happened.
So, the various live streamers investigate the castle to find a way to escape before their assumed death, they solve various puzzles both with their own wit and the help of their chat that were magical in nature. The various puzzles and traps were, genuinely, very fun to solve, both for the chat and the streamers doing them.
All the streamers manage to meet up again, and boy are they genuinely thankful for the fact that-so far at least, this doesn't seem to actually be anything life threatening and just seemed to be a grand time all around.
Then they all headed down a hall together, and the chat just went absolutely ballistic when they saw a large portrait of the witch and another man standing together and smiling.
The chat never got a good look at her before the streamers got teleported to different rooms, but that painting?
Because the woman standing in that picture-as pointed out by a chat member, looked an awful lot like Martha Wayne, and the man standing next to her? Thoms Wayne.
The streamers, obviously, think they've hit the jack pot because their viewer count is just going up and up because of this new information and also think they've hit some sort of scandal because, wasn't Martha Wayne dead?
Eventually, the find themselves sitting at the dining table with said woman who was silently drinking tea with a bunch of food sitting on the table in front of them. The woman smirked as she placed down her cup, asking if they enjoyed the various puzzles she laid out for them.
Everyone agrees, and the chat is exploding for them to ask if she's actually Martha Wayne.
She doesn't answer save for a cheeky smile and then suddenly they were standing outside of her castle and couldn't get back in.
Safe to say, reporters were flocking to ask various questions.