Rodney knows how the others see him. He's the annoying guy, the sidekick, occasionally the plucky comic relief; he's the one who's always underfoot, always in the way, never quite where he's supposed to be. He's the one who fills silence with chatter, with endless noise and words, because the sound fills the space around him, connects him to the people near him in a way that keeps him breathing, keeps him sane.
It's odd, he thinks, that he has no problem admitting to hypoglycemia and an allergy to citrus and a myriad of other ailments, but he refuses to bring this out in the open. Instead, he just makes his presence known and feels the people around him, keeping him stable and solid.
It's why he doesn't resist being put on an offworld team, even though the idea itself is utterly ludicrous; why should the expedition's foremost expert on – well, nearly everything – be sent out into the field? It's dangerous, it's messy, and it's the reason that lesser scientist are even on Atlantis, at least in his opinion. However, it gives Rodney a family of sorts, people he can always have an excuse to be around, and he relishes their overnight trips, though he complains loudly to anyone and everyone who will listen about them. They mean nights spent with people nearby, close enough to see and touch and feel, and he never sleeps as well as he does when he's crammed in a tiny tent with three other people.
It's why he spends a lot of time in the labs; scientists are a strange breed, running on strange hours, and there's nearly always someone else in there with him. It's not like he talks to whoever it might be, unless they've done something monumentally stupid, but he doesn't have to; there's always a hum in the room, the shuffling of papers or the sound of breathing or just the knowledge of a presence beside him. He stays until he can't stay any longer, until he's tripping over his own feet from exhaustion, and he makes his way back to his quarters slowly, talking to people in the hallway as he goes.
He hates his quarters. It's nothing against the room itself; he'd hate any other quarters just as much. There are some he'd actually hate more, the ones on the edge of the cleared living area, where fewer people have settled and he wouldn't have any neighbors. He hates the thought of the complete and utter silence that would inhabit his room should he ever move out there; this certainly isn't good, isn't great, but if he strains he can hear John next door or Teyla on the other side as they go through their own nightly rituals.
Sometimes he wakes up in a blind panic, sweating and hyperventilating, tears in his eyes threatening to fall because there's nobody, nobody anywhere and he's alone, the last person in Atlantis, and maybe Earth's gone too; but then he calms because John thrashes in his sleep, and his bed is just on the other side of the wall from Rodney's and Rodney ca hear everything that goes on in there. John's still in there, and Rodney can feel his breathing slow, can unclench his hands from the sheets and try to calm his racing heart because everyone is still here, still with him, and he's not really alone.
Some nights, though, John sleeps too deeply, and when Rodney wakes up he listens and listens and it just gets worse and worse, the panic welling up in his gut until it's physical. It makes him want to run for the bathroom, the twisting feeling, but he stays silent and still until he hears something, anything, a sniffle or exhalation or thump or anything because he doesn't know what he'll do if he really is the last one around.
Those nights, those nights are the worst, and a few times he's used his override code to let himself into John's quarters. John sleeps very lightly, all those years of military training engraved into his soul, and he always wakes when his door opens. The first time, Rodney didn't know what to do; he felt stupid, childish, the panic subsiding and his breathing evening out almost as soon as the door opened, but he's there again now so he can't just leave. Instead, he makes his way over to John's couch and drops onto it, pulling the worn Athosian blanket over himself, and falls asleep.
John thinks he has nightmares and never asks. Rodney thinks it's just as well.
It's just that he hates being alone, is terrified of it, and is even more terrified that if someone knows his true kryptonite, they'll have the ability to leave and to hurt him more than any physical torture ever could.