Because ya'll suck and have sucked me in, I'm doing some insane maths to figure out the timeline discrepancy between Iron Lung and Project Hail Mary.
To be clear, there is no world in which they REALISTICALLY and CANONICALLY could meet. So bare that in mind when making the AU: It will never work, don't try to use the canon, make some shit up instead. There is 300+ years of difference, that no lightspeed lightyear and g force motion can compensate for. Iron Lung is set in 2373-2378 Earth Years, the entire Quiet Rapture plot of IL takes place between 21 to 24 EIC years (That's post Colonization of Mars, in the IL universe. The EIC is the smaller number of years, and the QR starts in EIC Year 357.) Project Hail Mary, meanwhile, starts in 2017 with Grace's plot. It starts in 1975 for Rocky, because that's the year Rocky and the 23 Eridians set off for Tau Ceti. PHM ends in Earth Year 2051. Grace was in a Coma for 12 Earth years and 4 Light Years or whatever the FUCK relativity says.
NOW, One thing I think works to play around with mashing the AU, is to just remember that Stratt knew so many secrets. So many. What's one secret Mars Colony to add to it. Established in 1992, after the first handful of starts went out for Earth observers, the beginning of the Astrophage study, before it even reached Sol tbh. It takes a while for a Colony to work though, so you COULD say that Mars was the seeded colony in PHM, but the realized Colony in IL: Once Earth started to die, some people were ferried off to Mars, to preserve Earth resources, and because launching space ships created greenhouse emissions off the fucking charts and they were blowing up fucking Antarctica to try that.
So, like, you COULD say that IL timeline kicks into place AFTER Grace left for Tau Ceti. Somewhere around the 13 years into the Sol dimming, aka the star dying, aka tying into the insane IL Religious mythology. That maybe they started on Mars, like legit, and Simon (canonically btw!) was born on Mars after. Did I mention that Grace spent like, 16 years on Erid? Imagine he's already there then, by the time IL takes place.
Simon and his Mother (again canon) ship off to Eden in search of better life, they ALSO sit in a Coma for a long ass time, and through this relativity nonsense he catches up to Grace. Kinda. Like I said, you CANNOT follow the rules to make this AU work. Otherwise, you end up with dying and old Grace and young Simon, BTW (not a terrible combo but still).
(Actually, I think no matter what, you SHOULD consider that Grace is physically aged a good bit by the time he meets Simon. Just saying.)
So for the IronMary crossover to work, you should maybe plot out that the IL timeline starts roughly within the first Five (5) years of the PHM launch. It makes total sense that a private group invested in some spaceships and launched to Mars, to try and preserve some of humanity as it was beginning to panic. Then, later, the rest of Iron Lung filtering into place, time wise. But not plot.
Here's my addition to make the whole 'Stars and Planets are dying' part of the equation work: Most of it is a lie. Or rather, they don't know, and lie about that. But you can maybe work into it that the Astrophage has disrupted planet orbit, and sent some planets flying away by eating their atmospheres. That some starts finally blinked out, or were eaten. But more realistically? The Astrophage itself mutated, like all the mutated nonsense of Iron Lung loves, and became so DENSE it essentially ate ITSELF and turned into Dark Matter.
That Eden was lost, not the other way around, like the quotes in Iro Lung about whats more believable, the planets and stars all died, or the spaceships were lost and abandoned.
So, Astrophage mutates, becomes too dense, becomes Dark Matter, and basically the Petrova Line becomes a blank tear in 'space'. Huge swaths of 'space' eaten up, leaving big ole gaps between the observers. Eden just, lost radio connection and assumed the worst.
And all the Colony ships of Iron Lung are just people fleeing the dying Earth and Sol system.
The blood moons though, I'm still thinking on those. Maybe that's the Tau descendant, the way that Humans and Eridians are the Astrophage descendant (the book has so much more lore jesus christ)
Like, the Blood Moons are just Taumaeba, following the Astrophage, mutating with the change in radiations, becoming hungry little balls of living microbes (the blood ocean, which is 100% human by the way, could be explained this way. Because Taumaeba and Astrophage share a common Ancestor way on down, I'm telling you the deep dive is crazy work rn)
So, Blood Moons are just Asteroids that the Taumaeba colonized, mutated, and began hunting with. Following the new mutated Astrophage Dark Matter clumps, I.E the places like Eden that got cut off-- hence connecting the two universes.
That the Blood Eel and stuff, it's just mutated Taumaeba. Hungry little predators. And we know the Taumaeba can be changed to match Human consumption, just as likely it can change Human to match Taumaeba consumption.
My ongoing theory by the way is that the Blood eel wanted to fuse Simon into the hivemind/blood moon but like a blood transfusion, he had to be remade to fit the antibodies. So he was being slowly mutated to match the Blood Moon's biology. That it was kind of treating him like a male anglerfish, absorbing him to reproduce or to continue fresh life idk.
There's more, but mostly, once they meet in any AU that wants to be realistic and deep dive, you GOTTA just accept that Simon was hypoxic as FUCK, hallucinating, and just in general NOT DOING GREAT for the last half of Iron Lung. Most of that shit, from the moment he sees the mutated creature in the sub, is all in his head. There was probably never a flood of blood into the sub, he just hallucinated it because of the 1) Hypoxia caused by the poorly transmuted Oxygen from the blood around the sub and the O2 supply on board running out 2) EXTREMELY VIOLENT radiation poisoning from the camera and the moon itself 3) Heat stroke. A huge chunk of it is Heat Stroke giving him a full body hallucination and degradation. The Sub's cooling system was shot, the constant camera flash overloading it. He was being boiled alive.
(He probably just, broke his arm tbh. Someone mentioned he maybe burned his hands into the walls of the sub, or against the major pipework, and he ripped his skin off trying to get lose. I actually think it FROZE. That the pipes were trying so hard to compensate for the heat it froze like a bad AC coil, and he got complete and total frost flash freeze on the palm and arm. Whether it actually came OFF, IDK. Realistically, he pulled that fucker out of the socket and it got fucking annihilated, to the point it needed removal)
That any mutations Simon gets, are caused by the rapid and again violent radiation poisoning caused by the camera. Not the blood. But the blood itself probably was toxic when ingested, but he didn't ingest it, maybe. It's all really fucking weird man, I'm working on it.
