Got an idea for a bloodymary au that starts out like a normal modern au from Grces perspective. Grace just works as a teacher and meets Simon by chance. They start hanging out together, but Grace quickly realises that Simon was clearly hiding something. Something he was struggling with a lot.
Then, one day, Grace goes to sleep and suddenly wakes up on the Hail Mary, with no memory on how he got there. He only remembers his life up to the point where he went to sleep and nothing more. But when he eventually goes back to sleep on the hail mary he just wakes up in his old life. At first he thinks it was just a dream, but than it keeps happening. Every time he goes to sleep in one world, he wakes up in the other. And he also slowly starts remembering the petrova task force, even though in his normal life on earth astrophage doesn't exist.
So he pretty much starts playing out the plot of PHM in one universe while he tries to keep a normal life in the other and tries not to lose his growing relationship with Simon, even though he feels like he is going insane.
Eventually it becomes too much (probably right after they went fishing and he didn't know if Rocky will survive) and he tells Simon everything.
Simon tells Grace that the exact same thing has been happening to him since he was a teenager, only that his second life is in a much crueler universe, where he's currently sitting in the COI prison. Because of how hard his life in the second universe is, he's really messed up, even in the normal one, and struggles a lot, not wanting to go to sleep and go back there.
They learn how to help each other in the normal universe and grow even closer.
Shortly after that the events from Iron Lung happen and after he has died, Simon wakes up in the normal universe completely messed up from what he just went through. He completly refuses to sleep, knowing that he has just died in the other universe and convinced he will die for good if he ever went back there. Grace stays by his side the entire time, bit eventually they both fall asleep due to exhaustion.
Grace wakes up on the hail mary, wanting to go back to help Simon. Except now there is a strange looking ship right next to Mary that he and Rocky take a closer look at. And when they finally manage to get inside, he finds Simone in it, who wakes up shortly after being rescued.
From there on they just life a double life on earth and first the hail mary and later erid.
