Post canon Au idea for Iron Lung where somon was mutated into a mer like creature the size of the sub.
Since we know that Ellie was a amalgamation of humans (I think that's canon?? Idk I might be wrong), I headcanon that she wasn't always like this but gained her size and strength through eating and absorbing the humans that went down into the blood ocean.
In the movie when Simon first saw the light, we could hear a deep male voice saying "Agreed". Idk what's that supposed to mean but whatever I'm gonna say that it's Ellie asking her 'father' (I.e. the actual alien that lives on the moon/ the moon itself, either works) to keep Simon as a companion.
Simon is the start of a new fish so to speak. So in a sense, he would be an 'infant' of this new species.
After a while, maybe a few months or years post canon, the C.O.I, having confirmed signs of life started harpooning what they thought is the Alien species that lives in the blood ocean for study. They never caught anything until they did Simon.
Simon being railed in like a whale basically, and that's where he'll be for the next little while.
And that's as far as I got with my 4am thoughts lol, prob doesn'tmake sense but eh. And if u want this could prob work with bloodymary too with Grace being a newly transfered scientist or something. Idk.
