I'm not even sure what I'm doing...

So we could have a very wary and distrusting Simon being observed in a temporary habitat that he can breath in (Eridians are smart enough to figure out the sub is full of oxygen that could explode in contact with their atmosphere). He thinks he's an experiment to these creatures, but they are strangely kinder to him than humans. Maybe he makes a friend or two amongst them, maybe they learn his story and tell him that, while the stars around are dying, they are still there. And there is hope their people will come back with a solution. And maybe that gives him hope.

Eventually they make a bigger habitat with what Simon needs (and while he might be mutated enough to see in the dark or smt, he could use some light) And the Eridians could be able to replicate the seed and make him a garden, a forest even, for him to live in.

It's been a few Eridian year (46 days each) since Simon is on this planet, and he is totally fine being the only human on this planet, and he'll probably die before Eridani gets extinguished by the astrophage but it doesn't matter now because he has his Eridian friends and a garden with modified plants based on the few recountings of myths Simon's heard about of what Earth looked like and he's serene for the first time in forever.

And then news arrive to their side of the planet. They find out that Blip-A is back with a cure to save the stars like a year ago (yay!), but the sole survivor of that trip came back with an alien, and the more they describ it, the more Simon and his friends realizes that it's another human, who apparently gave his ship and abandonned the chance of going home to bring back the cure to Erid (who do not have the knowledge of making what the other human called 'beetles').

In that instance, I think Simon would panic. Weird spider-like, superintelligent rocks he can do, he faced the eel after all, but another human? He knows humans better than anyone else and knows how unpredictable and dangerous they can be (and still going by the Eden/quiet rapture perspective even though he figure he's either A) in a side of the universe where there are still stars, B) in the past, or C) in a different universe).

I think he would pace his biodome for days, wondering if or when he will have to meet that human (the other scientists are unfortunatly very excited to study human communication and social costums). And he tries to delay it as much as possible. Up to you to decide how he changes his mind (I'm too tired to think of one) but he does make the journey with his friends to the other side of Erid anyway as they want to meet the heroes who saved the stars.

They get to the other human biodome, and Simon finds it ironic it's a beach with an ocean, filled with water and not blood, he has to remind himself that it's not made of blood several times. They first meet Rocky, who is so excited to meet Simon and tells him that it will be a great surprise to Grace. Simon doesn't know that his name is Grace as it's really hard to translate from English to Eridian and back to English. Simon is also surprised but not shocked to learn the other human doesn't know of his existance thanks to Eridians long news travel. And Rocky just pulls him to the beach to meet Grace.

And it's during one of Grace classes that they meet, or more specifically Simon and the other Eridians watching Grace teach while Grace is too focus on his lesson to hear them arrive. Simon sees him and there's just this openess about this guy that he's never seen on any of the humans he's met in his life, it almost feel surreal. And maybe for a moment he is reminded of his mother and how she was the only light in his life and he sees this man in front of him, not an illusion or a trick, but just a human.

And eventually Grace notices him (maybe Rocky barreled at him to interrupt the class and made him look) and they both freeze like two cats meeting for the first time and not knowing what to do with each other. They've both been away from humanity for so long and Simon thought he would never miss it again, but in that moment he remembers that despite being part of an Eridian family now, he is still human, and kin recognize kin and gravitate towards each other.

Grace is the one who make the first move, staggering closer towards them and approaching Simon like he can't believe what he's seeing. Simon even hears him say 'This is real, right? Rock, you wouldn't pull such a cruel prank on me, are you?' and I think that's actually all he needs to get Grace in his arm and reassure him that he is as real as he is (reminder this is a Simon that has had time to grow and reflect on his past at least a little bit, and we all know behing the aggretion and the fear there is vulnerability and the possibility for gentleness with this guy)

(bonus point if one or both are touch-starved, and I want to see Grace cry)