In Iron Lung we do see Simon angry a lot, but honestly when it comes to his situation he’s still, like, disturbingly calm about it (this is bc he’s accepted the punishment, but I will elaborate on how he’s still weird). He flies off the handle a few times, but they’re all with good reason.

The first time (I can recall) that he really loses it is when he blasts everyone with radiation, but he does this as a last resort after nobody pays attention to his concerns about there being a monster with him in the blood ocean—Actually he does this as his last last resort, since he actually fucks with every button in the sub before walking over to the camera. And immediately after being told what the camera actually is he completely shrinks up, just mumbling “..i didn’t.. i didn’t know…” and he obviously feels really bad about it because once Jack comes back to talk to him (after being treated for the radiation) he awkwardly apologizes in the middle of their conversation.

He also yells at Ava when she comes back on the speaker, but that’s after an extremely vivid hallucination where he spoke to another “survivor” for god knows how long before realizing this entire person was fake. But, like, he’s yelling out of fear there—desperation, even—because now he’s scared that she’s not real either.

The only other time (I can recall) that he really flies off the handle is when his sub is being, like, actively attacked by Ellie, and I’d argue that’s not even “flying off the handle” considering how reasonable of a reaction it is to try and fight off a giant monster that’s not only chasing your ship but also telepathically harassing you.

Now, Grace? Ryland Grace? The guy whose life is average as all hell? Called another scientist “a staggering waste of carbon” for simply debating his “all life doesn’t need water to evolve” theory.

When it comes to Rocky? Grace literally rants to a camera about him just invading his personal space, that’s it. When Rocky moves in Grace is so bewildered and frustrated with the process of setting up his xenonite walls, and at that point in time the two of them were pretty much already friends.

I think the reason why everyone leans towards Simon being the more aggressive one is because his anger is taken seriously by the narrative, while Grace’s is played for laughs.

But let me just say, Simon is not aggressive, that’s not his first response—He’s afraid, but then he’s brave, we see this with the hallucinations he gets of himself (where he’s frozen with fear until he realizes he has to fight this thing off if he wants to be safe). He’s been almost completely stripped of his “flight” option, so that’s what’s forcing him to “fight”. (he still does run like hell as much as he can, though, as seen when he taunts Ellie and then slaps a binder on the control lever to speed away backwards) To me, most of his aggression honestly reflects an animal caught in a trap; He wouldn’t be acting like this if he could just run away.

Grace on the other hand? His first reaction is “fight”. No, he’s not beating the shit out of people, but that doesn’t mean he’s not fighting. He’s always fighting, and once “fight” doesn’t work, he’s absolutely on board with “flight” (as seen once he’s literally backed into a corner during his final conversation with Stratt), but that’s never his first reaction.

When they’re going to send him to space? He’s arguing like hell first, then he’s running. When he wakes up on the Hail Mary? Fights Armando, then runs away. When Rocky throws that xenonite map at the Hail Mary? Grace’s first thought is to say “shields up” like he’s on a sci-fi fighter ship, which implies he was fully ready to start blasting Rocky’s ship with lasers if that was the case; And even when being told there are no shields, his next instinct is not to fly the ship away, it’s to freeze in his seat as he sits and waits for what he assumed may be a missile to hit his ship.

In conclusion, Simon would not beat the shit out of Grace once they meet, he would instead run like hell. If Simon did, however, ever end up purposely hitting Grace, Grace would either hit back or yell at him.